"It's pretty hard to believe that there could be a guild as strong as Fairy Tail, huh Blue?" The celestial spirit shivered and nodded at Lucy, who was pulling her suitcase through the night. She was almost home and had already gotten her warning from the men on the boat about falling in. All that was left was to walk through the door but... She felt strange, as if she was being watched. Her steps became more brisk while Blue struggled to keep up.

The wind tickled the back of her neck as she walked. She was getting more and more uncertain of her being alone on this street. She walked under the bridge and was sure she heard the echo of footsteps, suddenly starting and stopping. The celestial wizard turned around for a brief moment, but not a soul was there. She was so close to her apartment, her brisk walking became slow running, with Blue being carried in her arms. She shot back around when she heard a twig break behind her. She quickly opened the door and rushed in.

"But I don't understand, are they really that strong?" Lucy asked.

"Please, they've got nothing on us." Natsu grinned.

"No, their strength equals ours." Erza shook her head. "If we were to engage in combat then neither side would survive. Their master, Jose, is also one of the 10 wizard saints, making him on par with master Makarov. As well as this, they have an elite group of wizards called the Element Four; they're similar to our S- Class wizards. Their magic each allows them to control a specific element. As well as them, a notable member of theirs is a wizard simply known as Undyne, whose main weapon is spears that are rumoured to pierce nearly anything and she is known to be able to render her opponents immobile. Their strongest wizard, however may be Black Steel Gajeel, an Iron Dragon Slayer."

"Dragon Slayer? You mean like Natsu?" Lucy asked, and Erza nodded, while Natsu simply scoffed.

"They do have... Another member, one which no one outside of Phantom Lord knows much of. No one really knows who this wizard is, but is simply known as 'The Phantom Judge'. Whoever it is must be a lot like Mystogan." The last sentence she did not say out loud; it was merely a thought in her head.

"Hey, you said that members could lurking around Magnolia, right?" She nodded once again at her friend's question. "I... I didn't feel alone out there. It was like someone was there with me."

"Someone followed ya here?" Gray frowned.

"I think so, yeah." Lucy replied. Erza narrowed her eyes. She looked through the window. When she was sure she had seen every area outside her house, she closed the curtain, preventing her from noticing the pair of eyes that lit up after she did.

(The next day, Phantom Lord guild)

"Sans! What are you doing?!" A high- pitched voice asked, waking the shorter skeleton from his nap.

"Just sitting here, trying to sleep." Sans yawned.

"I know you're sitting here! I meant why are you lazing around when there are jobs to do?!" He yelled.

"Because I'm tired, I guess." He said simply. "Say, why don't you go do some training with Undyne?"

"You're right brother! I'll go find her this instantly!" He ran off looking for his mentor and idol. He chuckled lightly at his brother's antics. He did get worried sometimes; Phantom Lord wasn't the safest guild by any means, least of all was it the friendliest with its hostile members and the provoking of its rival guild Fairy Tail, but he knew he could at least trust her to keep him safe. Keeping his brother safe was why he joined in the first place, but it was nice to know there was someone else helping. He didn't need to worry himself either, most people left him alone; he did have a tendency to blend into the background when he wanted to after all.

The door to the guild was suddenly blown open by a ball of fire, revealing dozens upon dozens of wizards, all angry and battle- ready.

"Huh. Those must be the Fairy Tail wizards." Sans looked upon them with a tired indifference, while Papyrus's eyes were wide with surprise. The wizards of Phantom Lord ran at the Fairy Tail members, who dispatched the wizards with ease. Sans could see a few notable and famous members of Fairy Tail. Natsu the Salamander, shooting fire at several wizards. Titania Erza, slicing through member after member, leaving no man unharmed. The most notable however, was the Fairy Tail guildmaster and member of the 10 Wizard Saints; Makarov Dreyar. the old man was walking through the hall, flicking away anyone who got in his way as if they were common houseflies. Despite his composure, there was an unyielding rage in his eyes. He went alone, leaving the other wizards to fight the masses.

"So he's going straight for Jose, huh?" Sans kept the smile on his face. "That's fine with me, not like I'm fighting or anything." As he said that, sword came his way. He dodged and looked for the source, finding one Erza Scarlet, but that wasn't what bothered him. When one went towards Paprus was when he began to fully take her seriously. He would've rushed towards him had there not been a crash inbetween the swords and his brother.

The smoke that developed around the two cleared, showing an armoured wizard, wearing a helmet with one eye hole. A group of swords buried under her fist. Undyne glared at Erza. She summoned several magical spears and threw them at the red- haired Mage, who jump up to avoid them and came down with a sword raised, only for Undyne's to block with another one of her spears. She thrust her weapon at Erza, denting her armour and blocking when her opponent struck with her sword. Undyne made several stabbing motions, all of which were avoided. Undyne ran forward with her spear, Erza mimicking the action with her sword. The two clashed and jumped back, staring each other down. Erza's body began to shine, revealing a different armour than before.

"Requip: Heaven's Wheel!" The armour was a shining silver colour, with dozens of swords floating around it. Undyne summoned some more spears of her own while Papyrus watched the fight with wonder. The swords and spears clashed, with new ones constantly coming into existence. This carried on and on, both sides never stopping until Undyne's at or got struck by one of the swords, denting it. Undyne glared at her opponent, before running towards her full- force. She blocked all the swords that came her way and jumped up, slugging Erza in the face. The red- haired wizard threw Undyne away, and summoned more swords, all of which went straight at the knight. While not piercing her skin they definitely did a number on her armour.

"Requires: Purgatory!" Her armour changed from one of wings and silver metal to a darker form, with spikes everywhere. She also carried a mace that was longer than she was. She jumped up at Undyne and brought the mace down. Undyne dodged, the Mace smashing the ground where she once stood. She summoned several spears and shot them at Erza, who used her mace to block them all before taking another swing at Undyne. Unable to avoid the attack again, she took it full- on. Spears appeared beneath her, slashing the armour. As she was blocking, Undyne lunged at her and she blocked with her mace. The two stood there growling at each other, constantly trying to outdo their opponent. This kept going until something broke Erza's concentration; a body falling to the floor; the body of their Guildmaster. He was completely powerless, his body turned a sickly green colour.

"Looks like Aria's been busy." Sans mused. "Guess this means Jose's plan worked." As the spirits of the Fairy Tail wizards broke, Phantom Lord began to overpower them. They were all eventually forced to retreat, running out of the guild with their master in their hands.

Once they were all gone, the entire guild was filled with cheers.

"We did it!"

"We beat them!"

"Those Fairy Tail weaklings didn't stand a chance against us!" They all had their little chants, but Sans didn't listen. He would've just dove off to sleep then and there had a familiar voice not called out to him.

"Wowie, that was so invigorating, Sans!" Papyrus said. "We defeated our assailants and our guild is still standing! Victory is ours!" Sans watched as his brother gave off his trademark happiness. Undyne leaning on the wall, panting for breath.

"She was strong. It's been a while since I've faced someone like that, especially one that could deal such punishment to me and my armour." She now had a grin on her face. "I can't wait to fight her again!"

"Well you'll have plenty of chances, this won't be the last Fairy Tail sees of us after all." Sans said.

Well that was my first chapter. Thanks for reading everyone. I'm probably going to add other Undertale characters. Here's a list of the ones I'll most likely include:

Alphys

Flowey

Toriel

Grillby

You probably won't see any of them in the Phantom Lord arc. Anyway, what Undertale characters would you guys like to see in the Fairy Tail world?