Though he automatically glances toward the hand moving in his direction, he doesn't flinch away. He freezes a little bit, but any contact--at least that which isn't violent--would get that sort of reaction. It's a gesture of uncertainty that he can't help, but he does settle again once Carl's hand is on his arm.

Though it doesn't make sense to him, he even manages to find some small reassurance in the touch on his arm. It's what allows him to work through his anxiety enough to meet Carl's gaze again and put his exact worry into words that he can sign.

'What if it decides to be cruel because we're close?' Just like what had happened every other time he'd actually felt this sort of pull toward someone. 'What if it sends you home?'

That's what he's most worried about. Almost all of the small handful of people he had admitted that he was close to were sent home shortly after, heading to their deaths. If he actually acknowledges how important Carl is to him, he's afraid that will be what sends him away forever.