US!Pap must have seen the stopping of his breath. (Even though he's a skeleton).
He chuckles, a large bone appearing in his hand. Error's soul skips a beat, a shiver running up his spine. He knew what was coming. Papyrus swung the bone, cracking upside Error's head. He screams in pain, writhing against his restraints.
Papyrus kneels down, forcing Error to look at him. "Where. Is. My. Brother." His tone was sharp, eyes narrow. He clearly meant business..
"I-I don't f-fuckun know!"
"Well I'd better be getting answers soon, might jog a little bit of memory." He swings it again, harder. A large snap could be heard. Error blacked out, his eyes filling with errors once more.
He had a large crack going up the side of his skull.

Blueberry wanders around the Antivoid aimlessly, his eyes filled with sorrow. The only thing that kept him going, was that maybe, just maybe, his brother would find him.
He sighs, placing the small red soul on the ground, and sat beside it. He had already begun to form small errors of his own, shivering and twitching every so often. He sighs, hugging his knees. The thought of home, only made him worse. Oh, how he missed his tacos, house, Snowdin...Papyrus..
His eyes droop down, tired from the never ending walk. Sans fell asleep in a matter of moments. Only, for a certain 'dreamy' Sans to enter his mind..