Night and day. There were as different as two things could possibly get. The warm, active and jovial day contrasted totally with the cool, subdued and mysterious night, and those who lived their lives in one or the other could not have been more different from those who chose the opposite. So it was that there were two ponies more apart from one another than any other; Princess Celestia and Princess Luna. Though the two were sisters, and undoubtedly loved one another, they had always been different. Celestia worked out in the open, an icon for all in Equestria to look up to and aspire to be like, greeting all with a friendly smile and a helpful word of advice. On the other side, there was Luna. While her absence from the world had stripped many of this generation of any real knowledge of her, her resurgence had given a good feel of the kind of ruler she was when compared to her elder sister. Like the night itself, she was subtle, often working from the shadows, protecting the citizens of Equestria not with advice or guidance, but with action, safeguarding their dreams and overall taking a more active role than her sister. Although, few in their nation would ever really know just how involved Luna was in their lives, since she was, unlike Celestia, somewhat less inclined to show herself, no matter how great her deed. And yet, to those who knew her, and truly understood what she did for their world, Luna was a valuable part of their lives.

But, as of this moment, she was not out in the night skies, protecting ponies from nightmares and restless nights, but instead, was simply spending time alone in her room, curled up with a good book. Although Celestia was often noted as the bigger lover of literature, Luna had her interests as well, largely the more ancient stories of their people, Starswirl and the like. And so it was that she was here, in her chambers, reading through one of the many chronicles of the old stallion, a small smile upon her face. Her chambers was, as one might expect of a princess of the night, dark and somewhat imposing. There were statues and tapestries of a far older age, most likely brought here to help give Luna a link to the past age she had come from. Needless to stay, it was in stark contrast to the more friendly and warm abode of Celestia, where anypony could feel they could walk into without fear of upsetting its occupant. But Luna paid no heed to her surroundings for the time being, given how utterly engrossed she was in her book. However, she found her hobby interrupted all of a sudden by a knocking on her chamber door. Although somewhat annoyed by this, especially given how little personal time she usually allowed herself, she nevertheless composed herself and smiled before calling out to those beyond her door.

"Yes?"

The voice that came back was a stern and gruff one, belonging to one of the thestrals, or "bat ponies" that served as the elite members of her night guard.

"You have a visitor, M'lady. Young Twilight Sparkle."

Upon hearing that name, Luna's face lit up, and she immediately put her book aside before getting up onto all four hooves. Gracefully, she made her way over to her door, using her magic to open it. Sure enough, there she was, Twilight Sparkle, looking to the princess as anypony would when seeing an old friend. Smiling more widely than before, Luna stood aside, silently allowing her fellow alicorn inside. Once the lavender mare was in, Luna gave a customary glance to the thestrals outside her door, both of whom gave an instinctive salute to her before resuming their previous position. The night princess gave them a nod before turning and closing the door behind her, after which she gave her full attention to the young mare before her. For the time being, no words passed between them, and Luna raised a hoof and gestured to a nearby pot of tea, silently asking her if she would like some. But, Twilight shook her head slightly, politely refusing the offer, to which Luna simply nodded in response. With that done, she looked over to a pair of comfortable chairs nearby, before then walking over to them, with Twilight close behind her. Once the princess had got herself comfortable, she watched Twilight get into a chair of her own, before then letting out a sigh and speaking up at long last.

"It is good to see you again, Twilight."

The young mare smiled at that.

"You too, princess. I hope you've been keeping well?"

Luna nodded before replying.

"Indeed. I have been most busy. There always seemed to be something to do at night these days, though I'll never complain about that. And what of your friends? I trust they are in good health?"

Twilight nodded and smiled.

"They're fine, all of them. In fact, Pinkie and Applejack have gone on a trip together. Turns out they might have a distant relation to one another, and have gone off to confirm it."

Luna raised an eyebrow, showing clear interest in that knowledge.

"Indeed? Well, that would be a most fascinating thing for them to learn of."

However, her expression soon became one of slight curiosity as she kept her eyes on Twilight.

"But...if you don't mind my asking, Twilight...surely you would know the answer to that, yes? After all, you still possess vast foreknowledge, do you not?"

Hearing that, Twilight shook her head a little.

"It's true, but...all I knew of this was that it was unconfirmed. Not really the kind of thing I can tell them. Besides, I know they just have an exciting trip together and...well...I guess I just didn't want to spoil it by giving the game away."

Luna nodded, understanding the young alicorn's reasoning. Regardless, despite how pleasant this moment was between the two of them, there was nevertheless a problematic feeling when the elder mare looked upon the younger. It wasn't helped by the fact that, every so often, Twilight would look away from her, as if ashamed to talk to her. Something was on her mind, that much was obvious, and as Luna spoke up next, her words were calm and collected.

"Twilight...I get the feeling that you did not simply come all this way to Canterlot for mere small talk."

Slowly, the younger alicorn looked to the elder, and the expression upon her face made it clear that, whatever it was she was going to talk about, it wasn't going to be good. But, having already been found out, Twilight knew there was little point in keeping silent about it any longer, and so, after letting out a long sigh, she began to explain.

"I...I came to talk to you...about...Tantabus."

Immediately, it was as if the whole world had frozen stiff. Luna looked to Twilight with utter shock, as if she were looking upon an entirely different mare. And yet, one look at Twilight's face made it abundantly clear that there was no trickery or deception at play here. Twilight did know about Luna's secret, although, in all fairness, it was something that the lunar princess should have predicted. After all, she had known for a long time now that Twilight possessed knowledge of the future. For her to know of this secret should not have come as any kind of surprise. And yet, hearing it out loud like this was nevertheless uncomfortable, and it prompted her to look away from the time being. Shame was all over Luna's face now, and her words were low and quiet.

"So...you know?"

Twilight nodded, a look of sadness upon her face, before answering that.

"I do, and...I wanted to talk to you about it."

Slowly, Luna closed her eyes and hung her head before speaking up again.

"Twilight...if you know of Tantabus...then you must also know why I created him. I..."

But, she was unable to finish those words, for Twilight then interrupted her, looking to her with an almost pleading look.

"Luna...I know why you did it. You wanted to punish yourself for what you did as Nightmare Moon. But...you don't need to do that to yourself!"

Luna turned to look at her, remaining silent as Twilight continued.

"I know you did bad things...but you spend a thousand year in exile. No matter what you did...that's punishment enough."

But Luna shook her head at that.

"Don't you see, Twilight? I can never forgive myself for what I did! I...I was a monster! I was the mare mothers used to frighten children into behaving themselves! I sought power over all, and even now...I still haven't paid for it! You...you have no idea what it is like to seek out punishment for yourself."

Hearing those words, Twilight narrowed her eyes.

"You...you think I don't? You think I don't know what it's like to want to be punished for your crimes? Because believe me...I do."

Luna looked at her, a slight look of confusion upon her face, prompting Twilight to continue.

"I...the things I did...I've never truly forgiven myself for. And I know there are those closest to me that will never forgive what I did. But...they're there for me. They don't want me hurting myself, like I almost did once. And I know there are ponies out there who want the same for you. Do you honestly believe that I, or your friends, or your sister, would want you to put yourself through this torment every single night? We've forgiven you, Luna."

But the words merely caused the elder mare to start welling up somewhat.

"And yet...I cannot forgive myself, Twilight. I...I did too much! I...I cannot...!"

However, yet again, she was halted, as Twilight leapt up and out of her chair, rushed forward and, in a move that would have shocked all of the nobility of Canterlot, embraced Luna in a hug. Needless to say, the elder mare was taken aback by this, and turned her head to look upon the younger mare. No words passed between them, and yet, Twilight's message was nevertheless clear; you aren't alone, and your friends want to help you. Moment after moment passed like this, with the two in utter silence, until, at last, Luna's tears began to flow. She sobbed openly, and finally returned Twilight's embrace. This secret, this pain she had kept on inflicting upon herself, had been a part of her ever since her return some time ago. And now, at last, she was letting it out. The tears came in droves now, flowing fast down the blue alicorn's cheeks, but all the time, Twilight held her close, perhaps the only pony in all the word who had some idea of what the princess of the night was going though. They had no idea how long they had stayed together like this, and in truth, they'd stopped counting the moments a long time ago. All they knew was that this tide, this wave of raw emotion was, slowly, coming to an end. Another sob came from Luna, and then another, before she finally stopped. Parting from Twilight, she raised a hoof, wiping the tears from her face, and seeing the smile upon the other mare, in time, she grew one of her own.

"Thank...thank you, Twilight. I guess...I needed to get that off my chest more than I thought."

Twilight nodded at that.

"We're friends, Luna. If you ever need somepony to listen...I'll be there for you."

The look of appreciation Luna gave the younger mare was a plain as day, and yet, it faded somewhat when a new idea began to grow in her mind.

"Twilight...you have known of Tantabus for some time, yes? Ever since you first moved to Ponyville?"

Slowly, the smile faded from Twilight's own face, after which she gave a grim nod, prompting Luna to continue speaking.

"Then...why is it that you only now come to me about it?"

Hanging her head a little, Twilight's words were tinted with sadness.

"I...I suppose I hoped that, knowing about my foresight, you'd have come to me about it."

Much like the younger mare, Luna gained a look of shame before leaning forward and placing a hoof upon her shoulder.

"I am sorry that I did not. I too had hopes of my own, that perhaps your knowledge did not include Tantabus. But it seems...we were both in error."

Though both were still saddened, they nevertheless let out a joint chuckle together. When that laughter stopped, Twilight looked to Luna, her expression an inquisitive one.

"So...no more Tantabus?"

Luna looked to her in silence for a time before, eventually, smiling and giving a nod.

"He has served me well, but...I suppose his time had come."

Twilight let out a sigh of relief upon hearing that, after which she gained a more serious look.

"Then I guess...there's only one thing left. A certain somepony who needs to know about this."

It took some time, but eventually, Luna began to understand what her young guest was talking about, and immediately, her face became one of nervousness.

"Twilight...I am not entirely sure if I wish for Celestia to know about this."

But Twilight maintained her serious expression.

"Luna...she needs to know...and deep down...I think you realise that."

Luna looked away for a time, and in the silence that followed, it was clear that she was deep in thought over the matter. When she finally looked back to Twilight, she nodded, albeit reluctantly, showing her acceptance of the young alicorn's plan. Twilight smiled at that, happy that her friend was willing to be so open about this. But, rather than say anything about it, she watched as Luna got out of her chair and started to walk to her door, no doubt ready to go off and speak with her sister at this very moment. During this, she looked back to Twilight and gave a look of slight irritation.

"Has anypony told you that you sound just like Celestia sometimes?"

Giggling somewhat, Twilight got out of her own chair before standing alongside Luna and giving her answer.

"Sometimes. And frankly...I can think of no higher compliment."