"Runnin' off fumes," he answered with another huff. The other Sans' took his sweet time getting back on his feet, his face an absolute work of rage. Now Sans knew why Frisk always looked so fearful when they fought in the past. He could look pretty scary when he wanted to.

Sans stood as well, keeping his stance defensive and summoning a barrage of bones at the ready.

The other growled, sending a shudder through the timeline native skeleton, and readied two gasters,"Y O U  T W O  A R E  M O R E  T R O U B L E  T H A N  Y O U ' R E  W O R T H." 

As he prepared for an attack, the foreign Sans launched himself at the pair, dragging his gasters with him, though when he was but a few feet away, he suddenly stopped and looked intently behind him. He didn't move for some time, and it was beginning to make his counterpart antsy, his fingers twitching in apprehension. But it came to an end soon enough as the other Sans let his hands fall to his sides.

"H-heh.... Fo-for-fortunately for yo-ou, I have.... O-other mat-t-ters to attend t-t-to-o,"he turned his leer towards the pair,"b-but don't wor-ry. I'll be b-b-ba-ck."

With that, the other Sans turned back towards the opposite wall and the same crackling sound from earlier echoed loudly as reality seemed to tear and welcome him into stark whiteness.

Sans stared at the scene in awe. Never before had he seen anything like this, and he might not ever again. As fast as he could, Sans ran after his double as he stepped inside the void and it began to close. "Wait," he shouted, but it was too late as the last seal disappeared with a strange vacuum sound.

Sans just stared at the spot for a moment, trying to process what had just happened.

He'd been right about the other universes, but never had he expected to actually meet another version of himself, much less fight him. Did that mean there were others like that Sans? Was there a Papyrus like that? Would they both come next time?

No, he didn't have time to think about this! 

Frisk! He had to take care of her first. And Paps. And help Alphys' with her research. And finished his own immortality research. And attend his sentry over the Underground. And actually start training. And act like all of this stress wasn't going to kill him. Then he could worry about them.

He could handle it. Right? 

Completely forgetting about everything as he lost himself in thought, Sans began to mutter to himself. His words were just a jumble of partially formed thoughts, nothing that really made any sense, but he couldn't help it. He absently reached to shove a hand in his pocket and only then snapped out of his trance, noticing he didn't have it on.