Disclaimer: I own nothing in this story. My Little Pony belongs to Hasbro. Thor, Odin, Laufey, Loki, and Bor belong to Marvel. I also don't own Thor and Loki's pony designs, they belong to lizzytheviking on Deviantart.

Celestia flew to Ponyville as fast as she could. The white alicorn had just been told by her sister about Discord's return and how he's possibly sided with the enemy. The two sisters landed in Ponyville, seeing the wreckage from the invasion.

"It's just as we feared, Luna. Loki has attacked the town." Celestia sighed sadly. "He and his army must've distracted us while we were defending Canterlot and Cloudsdale! Where are Twilight and her friends?!" Luna exclaimed.

"We're right here." Twilight replied as she walked over with the other members of the Mane Six, Thor, Spike, the Cutie Mark Crusaders, Pipsqueak, and Button. "It was horrible; you two wouldn't believe what happened…"

"We were attacked by Thor's adoptive brother and his army!" Pinkie shouted, making the Princesses' eyes widen slightly. "Calm down and tell us what happened." Celestia commanded.

The Mane Six, Spike, and Thor explained everything that happened from the barrier's collapse to Loki and his army's retreat.

"Apparently, our old enemies have sided with this creep who calls himself Loki. He's from Ponyheim. The members of his army are Gilda, Flim, Flam, the Diamond Dogs, and that showoff Trixie!" Rainbow explained. "I'm glad that fiend didn't destroy the entire town if it weren't for Thor." Rarity sighed in relief while nodding in Thor's direction.

"Thor, why does Loki hate you so much?" Fluttershy asked Thor nervously. "Sister, what's going on?" Luna questioned.

Celestia saw the ponies gather around her like they did last time, but their expressions were scared and hopeless instead of curious. The princess looked down sadly and knew what she had to say to them.

"I think it's best that we discuss this at the castle in Canterlot." She said with a grim expression. "Anypony who wants to stay in Ponyville is welcome to help repair the town. As for those of you who want to come to Canterlot…"

Some ponies decided to stay behind, but the ponies that decided to come were the Mane Six, Spike, Thor, and some other ponies who stood around the Princesses and Shining Armor. "Keep an eye out for trouble." Shining Armor commanded the guards before teleporting the Princesses and the ponies to Canterlot Castle.

At the Princesses' old castle, Gilda was a bit annoyed as she flew into the throne room while snapping, "What gives here?! We were so close to wiping them all out! At least we could've killed Rainbow Dash!"

"Exactly, we still owe her and her friends for the pain they've caused us." Trixie nodded.

"Everypony, you shall have your chance to kill them. Remember, the plan was to distract them with the invasions." Loki said calmly. "Granted, I wanted to finish off Twilight Sparkle and her brother."

He growled angrily and began pacing around while grumbling to himself. "You seem upset, but that's good." Discord commented.

"You would be too if you found out that your adoptive brother is working with the wielders of the Elements of Harmony!" Loki snapped. "Loki, you never told us you were adopted." Trixie commented.

"I am the son of a Frost Pony. That is all I will say." Loki grumbled to Trixie. "But still, a powerful alicorn like yourself who was abandoned as a foal and founded by Princess Celestia who gave you to Odin for him to raise you as his son would be impossible to get the throne since Thor is the oldest and he was there before Odin took you in." Trixie explained.

"Thor and I are not brothers by blood." Loki said. "Too bad that we didn't kidnap that dragon too." Gilda commented.

"He is a fool for calling me a 'dummy' whatever that means …" Loki grumbled. "Well, aren't we in a tempered mood?" Discord asked.

"Enough of this discussion, it is time we talk about some important matters." Loki commanded. "General Shield Strike!"

"Yes, sir?" General Shield Strike asked while approaching Loki. "How is our army doing?" Loki questioned in a dark tone.

"The Diamond Dogs and their soldiers are currently helping Flim and Flam with building their inventions and my soldiers are currently planning our next strategy." General Shield Strike answered.

"Excellent, then it shall not be long for us to plan our revenge." Loki smirked. "But remember the plan I commanded. Once the moment is right, the third part of our plan shall be at our grasp."

"Yes, Loki!" The members of his army nodded.

Meanwhile, the Princesses of Equestria had teleported with some of the ponies into the throne room in Canterlot Castle. Some of the ponies were panicking and asking questions while Luna commanded, "Everypony, calm down! This situation has gone to Code Red!"

"When the hay did we develop a terrorist system?" Dr. Hooves asked with a concerned expression. Celestia waited patiently until everypony was quiet before she spoke up.

"The kingdom has faced great threats in the past." Celestia began grimly. "From night, chaos, greed, to darkness. And, thanks to Twilight and her friends, they've been defeated. But this time…we're doomed because Loki will attack us."

"Who's Loki?" Derpy asked.

"The God of Lies and Mischief from Ponyheim, Equestria's neighboring kingdom. He's planning on taking over Equestria with his army and exterminating the entire pony race. You all saw most of his army, except for two of them. One of them is General Shield Strike who said to be the strongest warrior in all of Equestria until he and his soldiers were put in prison for a mass murder and killed a griffin with his bare hooves." Celestia explained. "And the other one is—"Luna began before the doors to the throne room opened.

"Your highnesses!" A voice called out. Everypony turned to see a Royal Guard running up to Celestia and Luna's thrones. It was the same guard who was standing by Discord's statue before he was freed.

"Captain Katoptris! You're alive! When the other guards found your body, they thought you weren't going to make it! Oh sweet Celestia, I'm so glad you're ok!" Shining Armor yelled. "I apologize, your highness. I cloned myself with my magic. When the spell wore off, I was barely able to escape." The captain explained.

"What happened? Ya look like you've been through Tartarus!" Apple Bloom asked. "Somepony unleashed Discord from his stone prison." Captain Katoptris said grimly to the ponies in the room.

"What?! Somepony released Discord?!" Fluttershy yelped in shock. "Yes, luckily, I survived the battle I had with him in Cloudsdale, but he's stronger than the last time you and your friends faced him." Luna nodded.

"Somepony unleashed Discord?!" Applejack asked as the ponies gasped. "Oh great, we unleashed the Lord of Chaos and Disharmony again!" Sweetie Belle groaned.

"It really isn't your fault, girls." Cheerilee reassured the Cutie Mark Crusaders. "I wasn't there, so I don't know what happened." Pipsqueak said.

"I wasn't there too." Button added. "Discord did a lot of things during our battle like summoning flying fish, winged serpents, and odd looking birds that sound like claws on boards." Luna explained.

Spike pulled out a board and ran his claws down it, causing some nearby ponies to cringe. "What? I just want to see what it sounds like." The baby dragon asked.

"Enough! I demand why Loki decided to attack the ponies here!" Thor demanded with an annoyed expression. "Thor, I'm guessing that he knows that you're willing to defend all of us from him." Twilight shrugged.

"Twilight, I think he already knows that." Celestia told her student. "Alright, do you mind telling us the whole story? We have to know these things!" Octavia asked.

"Awkward!" Pinkie said. "Tell me everything you know about Odin, Thor." Celestia commanded.

"Odin is my father and the ruler of Ponyheim alongside my mother. You and your sister were friends with him when you three were foals. He had lost his eye during the Frost Pony War." Thor explained. "So, who's Odin? Is he a pony?" Derpy asked.

"He's a pony…and he was our foalhood friend." Luna answered. The ponies gasped; although they knew about the alliance between Equestria and Ponyheim, they had no idea that their rulers were friends with one of the rulers of Ponyheim.

"Mind explaining everything?" Rarity asked. "It was a long time ago, after our teacher, Star Swirl the Bearded, left our old castle after he decided that we've mastered everything he taught us about magic…" Luna began.

"Ooooh! Go to a flashback!" Pinkie yelled in excitement. "Oh, Pinkie, you're so random!" Rainbow chuckled.

Flashback:

Celestia and Luna were seen as fillies staring out in the distance on a balcony at their old castle while thinking about their teacher, Star Swirl the Bearded.

"I sure do miss him, Tia. Do you think he'll come back?" Luna asked sadly as she stared at Celestia.

"I miss him too, Luna." Celestia nodded. "But I'm not sure if he'll come back or not…"

Suddenly, something white landed in front of them. It was an alicorn colt with blue eyes, a white mane, and a white coat with a light blue cube as a cutie mark.

"Who are you?" Celestia asked, noticing the figure. "My apologizes, I was curious about what was outside of my kingdom and ended up here." The colt apologized in a British accent.

"It's alright! What kingdom are you from? Are you the ruler's son?" Luna asked with a smile. "I come from Ponyheim, the neighboring kingdom of Equestria. And yes, my father, Bor, is the ruler of Ponyheim." The colt replied.

"Interesting…what's your name?" Celestia asked. "My name is Odin." The colt answered. "And yours?"

"I'm Celestia and this is my sister, Luna. We're going to be the rulers of Equestria." Celestia responded.

End of Flashback

It then cut back to the present as Celestia continued, "After that, Odin became our friend as we helped him become the ruler of Ponyheim while he helped us become the rulers of Equestria."

"It was entertaining, but hard while he helped us and we helped him." Luna added. "We understand, but what happens next?" Fluttershy asked.

"Well, then there was the day we defeated Discord…" Celestia began.

Flashback:

"Oh, how long will this take?" Celestia asked with a worried expression while she stood outside of a blacksmith shop in Ponyheim and gazed at where the border line between Equestria and Ponyheim was. "Discord has already messed up Equestria enough. Who knows how long our forces are holding him?"

"We can only hope that the blacksmiths can make us some powerful weapons for the two of us just in time." Luna reassured Celestia before turning to their friend. "And thanks for helping us out and letting us stay in Ponyheim for a while, Odin."

Odin, who was now the same height as Celestia and wearing gold armor with a yellow cape attached along with gold sleeves and gold armguards, nodded and said, "You are welcome, Luna, but do you mind if I suggest something?"

"And that is…?" Celestia asked. "Why bother make one weapon when you can do two separate ones? There could be three in each set or if you put them together, six." Odin explained. "They could represent different traits like those ancient weapons from a long time ago that my father told me about."

"Yes, these traits could be Honesty, Kindness, Generosity, Laugher, Loyalty, and one unknown." Luna nodded. "They could represent Harmony like the weapons." Odin added.

"Odin, you're a genius!" Celestia exclaimed with a grin when she understood the idea. "We'll call these weapons the Elements of Harmony! They could help us defeat Discord and bring harmony to Equestria!"

"Thank you, I try my best." Odin nodded.

End of Flashback

In the present, Luna continued, "Right after the Elements of Harmony were created, we returned to Equestria and used him to defeat Discord, turning him to stone."

"At first, we thought about killing him, but Odin said that turning him to stone could work because killing him seemed too harsh. Then, before the disappearance of the Crystal Empire, we stopped King Sombra and turned him into a shadow before sealing him inside the ice of the Artic North." Celestia explained. "So, what happened when the connection between Equestria and Ponyheim broke before the Frost Pony War?" Twilight asked.

"It was my fault…" Luna answered sadly. "It happened the day the Nightmare Mist turned me into Nightmare Moon."

Flashback:

Odin yelped as he dodged a spell fired at him. He watched in horror as Celestia was fighting Luna who had recently transformed into Nightmare Moon thanks to the Nightmare Mist possessing her.

"Luna, I will not fight you! You must lower the moon! It is your duty!" Celestia snapped. "Luna? I am…Nightmare Moon! My only duty is to destroy you!" Nightmare Moon said.

"Luna, you must listen to your sister and me! You must lower the moon and have Celestia make way for the dawn! This is not right!" Odin pleaded. "Weak as usual, I see…" Nightmare Moon muttered. "Join me and together, we can rule the kingdom!"

"I shall never join you!" Odin yelled. "You don't know the power of eternal night!" Nightmare Moon hissed in anger as she fired a spell at him which he dodged.

"I will never give into your temptations, Nightmare Moon!" Odin snapped. "Farewell, the night will last forever!" Nightmare Moon cackled while turning into her mist form and going through an open window, leaving the Princesses' old castle.

Celestia walked up to Odin who was staring in shock.

"Odin, is there a way to get rid of the Nightmare Mist?" She asked in concern. "They are not from Equestria or Ponyheim nor any other kingdom known, but why in Tartarus didn't we do something sooner?" Odin muttered to himself. "You didn't know that the Nightmare Mist possessed her because she was on night patrol, but we didn't act quickly enough! You must get the Elements of Harmony!"

Celestia gasped at hearing this, not believing that Odin said that she has to do this on her own without his help. "Odin, I can't kill my own sister! There's still good in her! I know there is! Please, you helped Luna and I defeat Discord, now help me defeat Nightmare Moon!" She begged.

"I only helped make the Elements, not help defeat Discord. This is something only YOU can do. I must return to Ponyheim to run my own kingdom." Odin explained with a grim expression. "You're my friend, Odin! You HAVE to help! We didn't agree to make the alliance between Equestria and Ponyheim for no reason!" Celestia protested.

"Do not worry, Celestia. If a disaster strikes in my kingdom, you will help me with it. Until then, good luck on defeating Nightmare Moon and ruling Equestria." Odin said before flying out an open window. "I'll try my best, Odin…" Celestia sighed, watching him fly towards Ponyheim.

End of Flashback

"Wow, that sounds deep…" Spike commented. "You all know what happened when I battled Nightmare Moon and banished her to the moon." Celestia said. "But when Equestria was recovering from the battle, Laufey, the leader of the Frost Ponies, attacked Ponyheim with his army, threating to plunge the kingdom into a new ice age."

"Wow, that must've sounded terrible!" Fluttershy said. "I sided alongside Odin and the Ponyheim army just as I promised him. The war cost Odin one of his eyes and soldiers wounded on both sides." Celestia explained.

"Why does this story sound so familiar to me?" Pinkie asked while scratching her mane in thought. "Oh goodness! I think Twilight told us this story once!" Rarity gasped.

"In the end, Laufey surrendered and the source of the Frost Ponies' power was taken from them. Right after that, he was executed along with the other Frost Ponies. As I was roaming around the Frost Pony Temple, I found a foal. It was small for a Frost Pony's offspring and he was abandoned, suffering, and left to die; I then realized it was Laufey's son. So, I gave the foal to Odin for him to raise alongside his wife." Celestia explained. This made Thor gasp slightly.

Applejack sighed and patted one of Thor's front legs while saying, "Aw shucks, that sounds cruel for the foal. Apple Bloom, Big Mac, and I were pretty darn upset when we lost our folks."

"So was I about mine." Rainbow added sadly. "Rainbow, are you going to be ok?" DJ Pon3 asked.

"I'm gonna be fine!" Rainbow sobbed. "But then, IT happened." Shining Armor said with a concerned expression. "After Twilight got accepted into Princess Celestia's School for Gifted Unicorns, got her cutie mark, and hatched Spike, her foalhood friend, Dinky…was killed."

"Remember the nightmare I had last night, Spike?" Twilight asked. "Yeah, I sure do." Spike answered with a nod.

"That was the one." Twilight said sadly.

Flashback:

In a cave, Loki growled as he paced around furiously while grumbling, "He could never have a Frost Pony sitting on the throne of Ponyheim...Thor and all of those ponies must pay."

Just then, he overheard some voices nearby. The gray alicorn smirked…finally, revenge!

"Wait, what was that?" Dinky asked nervously while hearing a sound. "Dinky, we can't mess around. I gotta get these plants back to the academy before sundown." Twilight said as she levitated a random plant from the ground and into her saddlebag.

A growl was heard which caused the two fillies to jump in fright. They looked around nervously, not knowing where the sound was coming from.

Dinky asked, "Twilight, what was that?"

"Why, it is good to see you two at last, ponies…" A voice hissed evilly. The two unicorn fillies gasped as Loki stepped out of the shadows. "Welcome to my temporary hideout…prepare to meet your doom!" He snarled.

"What do you want from us?!" Twilight demanded angrily while Dinky hid behind her. "W-W-Who are you?" Dinky asked with a frightened expression.

"I am Loki. You should never trespass on another pony's property, young foals…for there is a price you must pay." Loki answered insanely. "You can't tell me what to do!" Twilight retorted.

"How flattering…" Loki commented. "Now, hold still, so I can kill you quickly!"

He charged at Twilight with his horn glowing until Dinky head-butted him and stood in front of Twilight, blocking the alicorn away from her friend.

"Run, Twilight, run!" Dinky yelled. Twilight didn't protest and quickly ran off. Dinky tried to follow, but she was caught by Loki.

"Foolish filly, you cannot run from me!" Loki snapped. Twilight looked behind her in horror as Loki stabbed Dinky with a knife, killing her friend. "Dinky, no!" She screamed, seeing blood on the floor. "NOOOOOOO!"

"And now…you shall die!" Loki roared. He then attempted to attack her, but Twilight fired a spell at the ceiling which caused some rocks to fall and block Loki from her.

"NO! YOU CANNOT ESCAPE, TWILIGHT SPARKLE!" He screamed while breaking down the wall of rocks. But to his anger and shock, Twilight was gone.

"GRAAAAAAAAAAAAAAAAGGGH! THAT LITTLE BRAT HAD ESCAPED FROM ME!" The grey alicorn yelled furiously. "I shall have my revenge on her! She shall be one of the ponies who will suffer my wrath in the future! Once I take over Equestria, Twilight Sparkle shall be the first pony to die!"

End of Flashback

Twilight looked down sadly as she continued, "I told everypony I knew about what happened, so we went back to the cave and Dinky's body was nowhere to be found. I feared that Loki had removed the evidence, so he wouldn't get caught by the Royal Guards."

"Everything will be ok, Twilight. It's over." Her friends reassured her. "It seems like you all should head back to Ponyville." Celestia sighed sadly. "Shining Armor, can you teleport the citizens back to Ponyville?"

"Yes, your highness!" Shining Armor nodded before vanishing with the citizens of Ponyville and leaving Celestia and Luna alone in the throne room. "With everything that's happening, I really don't think Loki can be reasoned with." Luna said. Celestia nodded grimly.

"I have a feeling that this madness won't be over yet."