The other Sans went rigid as Frisk shielded her Sans. His bone stopped centimeters from the top of her head as he listened to her pleas. It was touching, really. Seeing a kid who actually cared about what happened to the monsters in this timeline.

But it didn't change the fact that she'd killed them all in cold blood before.

He let out a chuckle that slowly morphed into a maniacal laughter. And then he stopped and stared at her.

"H A H A H A H A H A H A A A A A!!!!  You two-wo-o are p-p-per-perfect! You think I'd s-sh-ow you some k-kind-a merrrrrcy ju-ust cause yo-you beg? I D I O T S,"he growled as the bone in his hand dissipated. With a snap of his fingers, threads fell down around her and wrapped themselves around her arms, legs and  neck, not tight enough to hurt, but snug enough they couldn't be shaken off.

Sans struggled at the sight, clawing desperately at the bone still pinning him. He could see the magic coursing through the threads and knew that whatever the other was doing, it wasn't good.

Horror crossed his features as he watched the other Sans wiggle his fingers, making Frisk's body move awkwardly in turn. "Frisk," he hissed out, voice on the edge of a shout, and getting his counterpart's attention. "H-h-heh, didn't thi-ink we'd leave y-y-ya out diiid ya? No-ow le-le-let's have soooome real fun," he grinned and moved his hand to send the human flying at the other skeleton.

Using his gravity magic, Sans pinned Frisk's body to the ground, hoping he hadn't hurt her as he muttered a quick apology. And then he noticed the gaster hovering right above her. It shot a beam at him, and he quickly teleported out of sight, taking cover behind another boulder as he panted for breath. All of this teleporting and fighting was taking a lot out of him. But he had to help Frisk. Somehow he had to break those threads and get her out of there.

The other Sans huffed in disappointment, bringing his human puppet to his side,"How doooo ya li-li-like that? Cow-ow-oward raaaaan away. Heh, weeeell at le-le-least I still have yo-ou." 

Just as the foreign skeleton raised his free hand towards Frisk, Sans teleported behind him and swept his feet out from under him, almost comically knocking him onto his face. But instead of taking the time to laugh at the scene, he quickly summoned a gaster and let it blast through the middle of the threads before taking Frisk's hand and teleporting a good distance away. He fell to his knees, exhausted, but didn't take his eyes off the other version of himself,"You ok, kiddo?"