Maybe Asriel's gotten more paranoid about being watched over these past few months, but he does manage to look back. When he doesn't see anything at first, he turns back to Chara and Frisk to continue whatever conversation they're having.

A few minutes later, he glances back again. A red light in the trees should be something startling, but Asriel perks up immediately. If it is Rinzler, there's a moment where he hesitates. Their last conversation was.... well, heavy, to say the least.

Asriel shakes off his nerves and gets up, wandering over to Rinzler's current stalking spot and looking for him. His disk is in plain view, slightly damaged from the planet before.

"Rinzler?"

He hopes it's Rinzler, otherwise this could end badly.