The sound shakes Rex to the core, and he immediately has a pang of regret. Fighting mindless monsters was one thing, but he hated causing people pain. Now he wasn't sure that even if this was a machine it couldn't think and feel. After Grimlock crashes to the floor, Rex recalls the nanites, getting the feedback of what exactly wound up happening. Temporary loss of power, nothing bad.

He gives a small sigh of relief, walking across Grimlock's back to slid onto the ground. He walked around to Grimlock's head, giving the robot a hesitant but friendly pat.
"It's ok, big guy, you'll be fine," he says reassuringly, trying to hide the twinge of uncertainty, and after a pause, "Besides it wasn't really a fair fight to begin with, you're, like, three times taller than me."