"It sounds strange, but before all this I was secretly hoping we could be friends." The skeleton commented catching his breath between spells after sidestepping her blade for the umpteenth time.

"Friends? Hmmph. Hold still and I'll send you to meet your friends." She sneered, dodging around the bone wall he conjured and swinging again.

"I thought the anomaly was doing this cause they were unhappy." he continued on, oblivious to her failed strikes. "And when they got what they wanted, they would stop all this."

He expected another swing, or one of the countless silent glares she had given so many of her victims. He hadn't expected her to start laughing. "What I want? You don't have a clue. What I want is this entire wretched world to pay, for taking him away from me!"

Sans staggered back. He hadn't been struck, but it felt like he had.

"Nomatter what I try, I can't save him, And I can't die with him, so what's the point?!" She screeched, before charging forward and managing to catch Sans' arm. The sound of metal chipping against bone sounded through the hall as the pain shot through him. Not a killing blow, but only because of where it had hit.

Until now he had been in complete control of the battle, Secure in the knowledge that he had his opponent completely figured out. every thought, every action... But this was a curve ball he hadn't seen, and now she was in control, and he was the one dodging an insane flurry.

"Save who?" He prompted, praying getting her talking would distract her enough that he could retake control of the fight.

Instead of answer directly, she just rambled in howling screeches as she charged slashed and swiped. "They called me a freak and threw me away, so I found a new family. They made me believe I wasn't broken. But I am, and it all went wrong. Because of them, I died for nothing, got my little brother killed, and tore what was left of my family apart!"

Ducking a swipe that actually managed to take a chunk out of a column, Sans was having trouble believing his eyes. No child should be able to swing a blade of any kind that hard. Using his magic he threw her to the side towards another bone wall. She just crashed through it, ignoring the cuts and scrapes it left on her. There was something else going on here, something supernatural at work.

"But you haven't died this time, you're standing right here." He shouted back. This was making no sense.

Charging again, she seemed to revert back to that eerie stare, stating in a cold monotone, "Frisk is here, Weak willed coward that she is. But I'm in control, and this place won't let me rest..."

That, was a possibility he hadn't even considered. Possession by a lost soul... The child wasn't even in control of her own actions? That complicated things immensely. Stopping a killer was one thing, but killing a possible innocent on the off chance that the thing controlling her might be destroyed with her... Could he even bring himself to do that?

"Who are you?"

"Death."

This was getting nowhere, he needed time to think. Lashing out with his magic he deliberately miscast a spell, trapping both of them in a single frozen moment until the spell completed, which it couldn't. Hopefully she would be unable to move or act as long as they were stuck like this.

If only there was a way to get the lost soul out... of...

"I'm an idiot."

Doing this to one who was still living would mean forcing them to the brink of death first. But the one in control wasn't a living soul. Reaching out with his magic it was easy to tell the twisted mass of hate and anger, from the kind timid soul buried behind it.

In a flash the battle was over, and the two combatants separated. She was crying, but at least she was free.

"It's okay, It's over now."Sans tried to sound reassuring, but was caught by surprise by his own voice. The former skeleton hardly recognized his own voice with how taking the soul into himself had changed it, and it wasn't just that, his entire form had changed. He was much larger now, and cloaked behind a shredded black robe that seemed to fade in and out of existence, taking the bones underneath with it.

The wraith understood Chara now, he could see all of her memories, her hundreds of cycles looking for a way to restore the monster that had been the first and only being the broken human had ever cared for. And he understood the possibility that her ability to 'save' moments in time being in his possession instead of Frisks presented...

Speaking again, sans added "and in a moment, it will all just have been a bad dream."

The moment just before Frisk entered the barrier chamber, with all of her friends close behind, in one of the previous cycles. That was where he needed to go.

The hardest part was making himself appear to be normal old not-powered-up-by-an-insane-lost-soul Sans, but after a few tries he got it.

The flower was so busy absorbing the entire underground it didn't feel one of it's captives break free, Staying out of sight until the battle ended. When all of the monsters had been restored, the barrier brought down and the prince's true body had just started to fade, he stepped in. Thank you. He felt come from the tormented soul the instant before it was consumed by the spell. Neither saw what he did, but when both Frisk and Asriel found themselves among the monsters as they regained consciousness, Sans knew they had noticed something change.

In the end Frisk got all the credit, after all this wasn't the underground that Sans had fought for, it was the one she had united. In a way, his entire world was gone, destroyed by the act of resetting it to an earlier, better, cycle. The memories he had brought with him from 'his' version of how things had gone, would haunt him for the rest of his life... but seeing the look on Toriel's face when she saw Asriel standing there, as if nothing had ever happened to her little boy? That made it worth it.