Antonius spent the following workdays training the PDF, the weekends he spent with Stormy in Ponyville.
Well, to be exact: Stormy was hanging out with the Cutie Mark Crusaders and he divided his time between helping the Element Bearers with their tasks, telling Lyra stories about mankind (she could not get enough of them) and visiting Zecora to learn about the Everfree as soon as the potions she had made were ready.
For security measures, those potions were kept in Princess Celestia's private safe.

In addition to that, he taught Twilight and her friends the basics of close combat, building on their abilities they had shown when he had evaluated their prowess; Rarity was surprisingly proficient with her front hoofs, Twilight used magic even at melee range and Fluttershy... was good at dodging.
The other three ponies had changed their styles a little. Rainbow Dash used a technique that reminded Antonius of martial arts, Applejack brought her hind legs to bear and Pinkie showed a tendency to weaponize her environment or even pull her party-cannon seemingly out of nowhere to shoot confetti and streamers with a kinetic force not to sneeze at. All told, he was content with their progress.

Then, it was the last weekend before the celebration the ponies called 'Hearth's Warming', where they commemorated the founding of Equestria. That was everything Luna had wanted to tell him, because she had not wanted to 'spoil the pageant'. So, there obviously would be some kind of theater play. Well, why not.
Furthermore, she had asked him to take part in and enjoy the celebrations, and since they did not sound heretic, he had agreed.

However, this 'Hearth's Warming' would not be the only notable event in the next few days: Tomorrow, Moonlight and Blackwing would return from Coltport - and move in with him and Stormy. Antonius' plan was to slowly withdraw from the newly created family and give them time to really get to know each other without interference.

Today was probably the last time he was in Ponyville as Stormy's 'chaperone', and Stormy spent it - as usual - with the Crusaders. Antonius just entered Twilight's library and found her and Spike with a big scroll.

"Hello, Twilight," he greeted,
"busy today?"

"Yep," Twilight answered,
"I'm going through my to-do-list for Hearth's warming! I'm just looking if... one moment... yes, I already have got all the presents for my family and friends!"

"Yeah, just like the last two times you checked that," Spike mumbled.

"Presents for family and friends?" Antonius asked.

"Of course!" Spike shouted,
"what would Hearth's warming be without presents?"

"Still a very nice holiday," Twilight corrected his attitude and nudged him,
"a time to remember the love, friendship and harmony between you and your family and friends."

"I thought it was about the founding of your country," Antonius interjected.

"That, too," Twilight explained,
"but I'm afraid I can't tell you more, since I promised not to spoil the pageant for you."

"Is everypony in on keeping me in the dark about this celebration and the pageant?"

"Hmm... I think there might be one or two who don't know - but don't start looking for them!"

"No worries. I guess this pageant is quite a 'big thing' then, hmm?"

"Of course! My friends and I will even take part this year! What an honor!"
She suddenly winced.
"Oh dear. Was that supposed to be a secret, too? You didn't hear that, okay?"

"Okay," Antonius smiled,
"I did not hear that you and your friends will take part in the pageant."

"Umm... thanks... anyway, where did I stop? Right, the presents."

"I have a question about that: Who is giving what to whom?"

"Everypony. Something nice. Family and friends.
Wait a second... you don't know that? Of course you don't! Sorry, Hearth's Warming is such a part of our social life that everypony's familiar with it, and because of our little 'vow of silence', we forgot to tell you our customs! But don't worry, nopony will expect you to throw presents around."

"Correct me if I'm wrong, but that only works if I don't get any presents, either, otherwise receiving without giving would be against the principle of mutuality commonly found in friendships... so I should hope that I don't get any presents."

"Well, I would not exactly count on that..." Twilight admitted with a forced smile.

"So you know that somepony will give me a present?"

"Umm... yes."

"Who? Wait, it's probably Luna, isn't it?"
Twilight just kept her forced smile, so Antonius continued:
"Aha. Okay. Mind if I leave now? Completely unrelated to the fact that I actually have to get some presents for... for whom?
Luna? Yes.
Stormy? Yes, definitely, fillies certainly like presents.
Celestia? Hmm... probably."

"Yeah... and me and my friends..."

"All six of you?"

"Sorta..."

"Whoa. And with my duties, I only have little time left... I better get going. Bye, Twilight!"

Antonius left the library.

Damnit. How many of those blasted presents did he need?
Stormy, the Princesses, the Elements... nine. He had to come up with nine presents... if he didn't count Moonlight and Blackwing, that is. Or Lyra and Bon Bon. And Zecora?
No, he would concentrate on the ponies who he knew were going to give him a present, so he needed nine ideas for presents.

First: Luna.
And there was the first problem: What do you give to a magical pony princess who should already have anything she wanted? It probably had to be something rather new... idea!
Antonius went straight to the Carousel Boutique.

"Hello, Rarity," he greeted,
"do you have a moment?"

"Of course," she answered,
"how can I help you?"

"I just learned that it is a custom among you ponies to give presents to each other on Hearth's Warming. Now, I need your opinion: Would a set of socks be a suitable present for a pony?"

"Oh, definitely. As I already told you, they are great casual wear! Whom do you want the socks for?"

"Princess Luna."

Rarity looked surprised.

"Princess Luna? There's a little problem... I'm afraid I haven't got her measurements."

"No problem, we can determine them with the help of my memory. I'm positive I can show you the size of her legs with sufficient accuracy."

"Oh, well, it's worth a try, I guess? Okay, Antonius, let us begin."

Thanks to his advanced memory, Antonius was able to provide Rarity with enough data so that they could determine the needed measurements. Rarity seemed to be quite amused by the fact that he could show her the circumference of Luna's legs at any given height - especially when they reached the upper part of Luna's hind legs. Antonius chose to ignore this and thanked Rarity for her help.

As he was just about to go, he turned to her again:

"About the payment: How do you want me to pay you? Usually, Luna is invoiced, but in this situation, that is out of the question."

"Don't worry, I won't take money for this."

"Are costless presents considered to be valid presents?"

"Of course!"

"Okay. Thanks again. One done, eight to go. Oh, by the way: Is there anything you want as a present? Now that I think about it, I should also have asked Twilight... I'll do that later."

"Oh, just surprise me..." Rarity said, then she raised an eyebrow:
"Please wait a second: 'one done, eight to go'?"

"Yes, one present for each pony who I know is going to give one to me, so that everything is mutual."

"How do you know that... Twilight spilled the beans, didn't she?"

"Rather accidentally, but yes, she did. And I'm glad she did, otherwise I wouldn't have had any idea of this presents trouble."

"Antonius, I think you are missing the underlying idea of this custom. It's not just an exchange of material goods, and you should not feel obliged to give somepony a present."

"Oh? Well, be that as it may, I better get going again."

Antonius left the boutique.

Rarity kept looking at the door for a few seconds. Antonius tried to adapt to their customs, but he obviously didn't get the point of Hearth's Warming, probably due to his different cultural background.

Now, if she didn't do anything about it, she would get some kind of present. If she intervened, she would probably get nothing. Of course, presents were nice, but more important was the right reason to make them.
As the Element of Generosity, she just had to do something about it. She left her boutique and headed towards Twilight's library.

She met her friend about halfway.

"Hello, Twilight," she said,
"I just had a slightly troubled visitor who was convinced he has to come up with some presents for us."

"Yeah," Twilight answered with an awkward smile,
"it is possible that he got that impression. He concluded plausibly that he has to give us presents if we give him presents. Then he left."

"Same here. I tried to tell him that presents are not a necessity, but he was a little too caught up to get that. I guess he is running around Ponyville trying to find something he can give us."

"Hmm. I'm trying to find him to set the whole matter right. Perhaps we should get the girls, that will increase our chances of finding him."

"Good idea."

Second: Stormy.
Done, thanks to Fluttershy's help.

Third: Celestia.
Well, that was a problem similar to the one he had had with Luna's present, but this time, he couldn't use the Luna-solution. Giving similar presents to different ponies would probably be considered unimaginative, and that would without doubt not be beneficial for the concerned friendship.
So, what to give to Celestia? The Princess of the Sun?
Umm...
Sunglasses?
Sunscreen?
A sunshade?
Something that did not start with the word 'sun', perhaps?

Antonius was annoyed. He had had just two ideas for presents and he needed seven more, but he seemed to have run out of creativity.
He noticed that Rainbow Dash was just passing in the sky above him, but that did not inspire him at all. He thought hard, but the only effect was that he started feeling the urge to punch something.
Somepony should have told him that friendships with ponies could become so complicated.

Antonius had walked through Ponyville for some time, hoping for an usable idea, when he heard Rainbow Dash shout:

"There he is! I told you I saw him earlier!"

He turned around. All six Element Bearers were running up to him.

"Antonius!" Twilight exclaimed,
"Good thing we found you!"

"What's wrong?" Antonius asked,
"is there a problem?"

"Actually, yes, there is," Rarity told him,
"you seem to have misunderstood the meaning of Hearth's Warming."

"Huh? As far as I know, you celebrate the founding of Equestria and friends and family exchange presents."

"That is what happens, but it's not the actual meaning," Applejack said,
"it's rather a time to cherish your family and friends. The presents are not important."

"Why do you make sure to have a present for each of your friends, then?" Antonius asked.

"Well... to show them that we value them?" Twilight said hesitantly.

"So, presents are sort of necessary in your culture to prove your friendships," Antonius stated.

"No, silly," Pinkie Pie corrected him,
"presents may be nice, but nopony will think you don't value them just because they get no present from you."

"And the best present you can give to your friends is not some knick-knack, it's your friendship, love and support," Fluttershy added.

"Yeah, that sounds sappy, but Fluttershy is totally right," Rainbow Dash agreed.

The other ponies also voiced their consent. Antonius was slightly confused.

"So," he started,
"you give each other presents as a visible sign of your friendships. Despite there being no need for that, since your behavior towards each other is better suitable for proving those friendships."

"It sounds totally weird if you phrase it like that," Twilight sighed,
"look, it's a custom... a nice touch... what would you say if I gave you a present?"

"Thank you?"

"Would you suddenly like me much more because of that?"

"I don't think my level of 'liking you' would change significantly."

"Okay, now, if I didn't give you a present, would you suddenly hate me?"

"No. That would be a ridiculous overreaction."

"See it now? Presents are nice, but not necessary in a true friendship, okay? What kind of friends would we be if we demanded presents from each other?"

Antonius was silent for a second, then he said:

"You have some weird customs here, but I think I get the drift."

"Finally," Twilight sighed in relief,
"and to prove that, we want you NOT to give us presents."

"No?"

"No."

"And you won't give me presents either, right?"

"Oh, we will still give you presents."

"Huh? That would violate the principle of mutuality."

"Yes! But we don't care!" Twilight screamed, half in supplication, half in exasperation.

"Oh. Okay, as you wish. But what about my presents for the Princesses and Stormy?"

Now Twilight hesitated.

"Well, fillies usually get presents, and thinking about how closely you work with the princesses, presents would certainly..."
Rarity nudged her forcefully.
"... still not be necessary!" Twilight quickly finished.

"Hmm," Antonius said thoughtfully,
"truth be told, I would still like to get at least those three presents. I know I don't need to, but it still feels right somehow."

"I think he's finally got it!" Pinkie cheered.

"Yeah," Applejack agreed,
"now, what do want to give to them?"

"I've already got Luna and Stormy covered," Antonius told them,
"I just lack an idea for Celestia."

The ponies looked at each other.

"Well, a present for Princess Celestia is certainly difficult to choose," Twilight admitted,
"I usually look for an extremely rare book that is not already in the Royal Library. Finding one gets harder every year, though. Perhaps..."

She started smiling.

"Antonius, I've got it! You have learned a friendship lesson today, haven't you?"

"I have what?" Antonius asked in confusion.

Twilight's friends started smiling, too.

"You have learned something about friendships. What do you think about writing a letter to the Princess and telling her what you have learned?"

Antonius stared at her, dumbfounded.

"You are kidding."

"Not at all!" Twilight laughed,
"and I guarantee she will like it!"

A short time later, they were in Twilight's library and Antonius was sitting in front of a blank scroll, a pencil in his hand.

"Okay, now, any suggestions how I should start?" he asked.

"Just write something like 'Dear Princess Celestia', and then tell her what you have learned. That easy," Twilight said.

"Well, if you say so..."

Dear Princess Celestia,
hello Tia,

today I learned a lesson about friendships. I had recently learned about the custom to give presents to your friends on Hearth's Warming, and I thought that I had to come up with presents for everypony who also has a present for me.
Now, the Element Bearers told me that this assumption was wrong, presents are actually an unnecessary sign; nice, but not that important.
A true friend does not need to be 'bought'. He/She cannot be 'bought'.
If a friendship is dependent on material gifts, it is worthless.
A true friendship is independent from knick-knack of that kind, it is sustained by love, care and support for each other.
Yes, that's sappy.
Nonetheless, it's true.

Your little sister's second in command,
Antonius Varus
(actually Ultramarines 2nd company)

P.S.: I did not miss the irony in giving you this letter as a present.

Antonius put away the pencil and rolled up the scroll.

"Great!" Twilight laughed,
"this is a great friendship letter! And it's also so very much you!"

"Thank you," Antonius answered,
"now, are you sure you don't want presents, too? Not even voluntary ones?"

"No, don't you dare to get something for us!"

Antonius and the ponies stayed in the library until afternoon. They told him about some of the friendship letters they had written to the Princess and the stories connected to them. They also agreed to meet at the Canterlot station the next day, so that Antonius could take the presents for the Princesses and Stormy.
Then it slowly got time to return to Canterlot.

"Goodbye, my friends," Antonius said,
"I'll pick up Stormy and get to the chariot."

"She's probably at the Crusaders' clubhouse. I'll accompany you to Sweet Apple Acres," Applejack offered.

"I'll join you for a while, too," Fluttershy said.

So they left the library and headed towards the Apple farm.
They found Stormy and her three friends just outside Ponyville, babbling something about 'Cutie Mark Crusader Tunnelers'. They looked accordingly.
Applejack picked up her little sister, Antonius picked up Stormy and they all said goodbye and parted ways.

"Well, Stormy," Antonius said on their way back to the waiting chariot,
"I guess this evening will hold a bath and a preening session for you. Tomorrow, Moonlight and Blackwing will arrive, after all, and you don't want to look like a moving little mess, do you?"

"No, of course not. I'm really looking forward to seeing them again," Stormy answered.

The next morning, Antonius, Stormy and Luna were waiting on the landing platforms. It had started snowing about an hour ago, and the snowflakes already covered the ground in a thin layer.
They had to wait just a few minutes, then the expected chariot came into view. It closed in on the platforms and came in to land.

"Hey, there is somepony onboard I have not expected," Antonius said.

"Neither have I, but it surely is a welcome surprise," Luna replied.

The chariot landed, and Moonlight, Blackwing, and Rapid Cure got off.

"Hello, Moonlight and Blackwing. How are you?" Luna greeted them.

"I'm fine," Moonlight answered with a small smile.

While her fellow passengers just wore scarves, she had donned a dress that covered her whole body. Only her head, neck and hooves were still visible.

"I'm happy to be back home," Blackwing grinned.

Luna turned to the third pony:

"Hello, Doctor Cure. What brings you here?"

"Well, as the 'specialist' for this specific kind of injuries, I thought it would be a good idea to stay close to my patient. So, I applied for a transfer to Canterlot General. The clinic administration approved it, and here I am."

"That's good news. Now, lets us get inside. There is no need to stand here in the cold."

A short time later, they were in Antonius' and Stormy's quarters - now Antonius', Stormy's, Moonlight's and Blackwing's quarters. An additional bed had been set up in the room, as well as an extra table, chairs and a cupboard, all of them pony-sized. The personal belongings of the batponies had also been transferred to this room.

"Well, that's for sure better than the barracks," Blackwing grinned.

They stayed together until after lunch, then Luna went to bed and Rapid Cure left to meet with the moving company he had employed to ship his personal belongings to Canterlot.

In the afternoon, Moonlight and Blackwing asked Antonius a lot of questions about what had happened in Canterlot and Ponyville while they had been gone. They were not completely unaware of some of those events, though; they had gotten letters from Gentle Breeze.

Later, they made a stroll through now snowy Canterlot before they met with the princesses for dinner.

After that, they returned to their room for some more games and harmless merriment.
Moonlight, however, seemed to become a little tense now, she often changed the way she sat or lay. Suddenly, she asked:

"Umm, Antonius, would you mind if I took off my dress? Sometimes, my scar's getting a bit itchy if covered for too long."

Aha, so she was not completely 'fine' again.

"Why should I mind that?" Antonius answered with a question of his own.

"Well, my scar is not exactly pretty."

"It is a sign that you did your duty in the face of adversity. Look at my scar. Do you want me to cover it?"

"No, of course not."

"Then, you should feel free to be undressed any time you want... oh, that sounded weird."

Moonlight snickered and took off her dress. The scar was still clearly visible, but the fur around it had grown back. Antonius could only see about half of it, since Moonlight carefully covered the rest with her tail.

"Feeling better now?" Antonius asked.

"Yeah, thank you," Moonlight answered.

"May I have a look at it?" Stormy asked shyly.

"Huh? Sure, Stormy, but are you not... well... a little disgusted by that scar?" Moonlight asked insecurely.

"What? No, not at all. You got injured when you saved my life. So, how could I ever be disgusted?"

Moonlight was obviously relieved to hear that. She grabbed Stormy and cuddled her. The little mare laughed and hugged her.

Later, they got ready for bed. That included handling the line that formed in front of the bathroom.
Despite trusting the two batponies, Antonius chose not to disable his alertness, just in case anything should happen.

It was after midnight when this alertness woke him up. There was movement in the room. He opened his eyes and saw Moonlight, walking through the room in his direction.

"Moonlight?" he ask quietly to avoid disturbing Stormy.

She did not answer, but she kept approaching him. When she stood next to his bed, she made a little jump forward - and bit into his neck.

What the hell? That was quite a surprise.
Antonius quickly noticed, however, that this 'bite' hardly deserved that name. It could not harm anything more resilient than an earthworm.

"Moonlight, what the hell do you think you are doing???" he asked quietly, but she still did not answer.

Antonius carefully grabbed her and pulled her away from his neck a few centimeters. She started hissing and bared her teeth. He let go of her again, and she was back at his neck.

Damnit. He should better get some help.
He grabbed a cushion and threw it at Blackwing. The batpony stallion jumped up - and fell out of his bed.

"What's going on?" he asked sleepy as his head appeared again.

"YOU tell ME!" Antonius hissed.

Blackwing shook his head, then he looked at the strange scene.

"Oh," he said.

"Oh?" Antonius asked,
"That's hardly an explanation! Why has your wife come over to bite me?"

"Umm, do you know sleepwalking?"

"She's sleepwalking?"

"Well, when you're a batpony, it's more like sleephunting."

"What? You are kidding, right?"

"No, it happens to her when she's very nervous. Today, she was very nervous. She wanted to make a good impression on Stormy. But I can assure you it's not dangerous, she doesn't really bite, or does she?"

"No, she doesn't. Can you still get her off of me?"

"Nope. She's very persistent once she has bitten on."

"Great. Now what are we supposed to do?"

"Pet her back."

"WHAT?"

"Trust me. We got to know each other that way. It may have been a bit embarrassing, but it was quite funny. Pet her back, and she will stop biting you."

Sometimes, Antonius had the impression that he had determined the true meaning of the universe: it existed solely to make fun of him.

Having no better idea, though, he started petting Moonlight's back.
The good news was that she really let go of his neck.
The bad news was that she crawled into his bed and made herself comfortable between his chest and his arm.

"Blackwing! What the hell is that supposed to mean?"

"She's still asleep. It's no use trying to get her out of your bed, she will just aim for your neck again. Just let her sleep. If she starts stirring, just pet her back again."

"That's all?"

"Not exactly," Blackwing grinned,
"if you pet her flank, she will start hissing and biting again. And I will get jealous, so don't do that."

"Thank you," Antonius deadpanned,
"you have been a wonderful help."

"You're welcome," Blackwing snickered.

So, Antonius spent the night with a sleephunting batpony mare in his arm. It was really astonishing how this planet managed to steadily increase the level of weirdness.

The next morning, after a short and light sleep, Antonius still waited for Moonlight to wake up. Stormy woke up first, however, and found the event of the night hilarious.

Then, there was a knock at the door and Luna came in. She took a look at the scene and stepped up to Antonius.

"No. Comment," he said sternly.

Luna grinned and whispered into his ear:

"And I thought I was your personal cuddly-pony."

"I'm certainly not responsible for this!"

"I know, she was sleephunting. That also explains the strange dream she had last night."

Huh?

Now, finally, Moonlight woke up and yawned. She opened her eyes, only a bit at first, then, as she looked into Antonius' face, wide.

"Huh?" she asked with a blush and in total confusion,
"oh, sorry, umm... did I sleephunt you?"

"Indeed," Antonius answered.

Luna, Blackwing and Stormy burst out laughing.
Well, this living community certainly was 'interesting'.