This sort of thing was such a pain. If he didn't think they'd make his life difficult later, he would have just made them come with him, but even he knew that forcing anyone go to the Hyperion would make Cordelia frown at him. And he didn't particularly want Cordelia frowning; it always made him feel rather bad to see it, and Mantis did not like feeling bad.
"Psycho Mantis," he stated at last, shifting slightly on his feet. "You are Skyfire. He is Starscream. Introductions finished." His hand made an impatient, grasping gesture, tension stiffening his skinny shoulders until they were nearly ramrod straight. The shower shut off, and a moment later, Starscream was exiting, a towel around his shoulders and track pants clinging loosely to his hips---at the sight of the intruder, he was immediately defensive, stepping protectively in front of Skyfire with a growl in his throat.
Mantis didn't seem impressed, not budging except to tilt his head slightly in a curious, familiar gesture. There was something about the smaller one that reminded Mantis of himself, actually. Perhaps it was the way his mind worked.
"Human girl and Autobot will arrive soon," he added for Starscream's benefit, struggling to keep his speech coherent and his words clear. "Autobot will not like Starscream. Best come to Hyperion. Protected there; will teach how to be human."