Sora doesn't appear to notice the petting at first, and nothing changes? It's more like as the soldier's adrenaline dies, the miasma of darkness surrounding Sora melts away, disappearing into the darkness of Beacon or sliding back into Sora, soaking up his feet and into his skin. And as that happens, Sora stops trying to get his hand out of the trunk. No change in expression whatsoever, still on its haunches, other hand limp on the ground. It's not like there's a tail or anything for it to express emotion. (If it has any?) The little tendrils drifting off of him are just that - tendrils. About as expressive as smoke from a fireplace.

Nah. All that happens is that its head starts bumping into Soldat's hand. Is there actual communication happening here? Who knows! That seems to be a thing it's chasing, though. Congrats, Soldat, you've reached dog mode. Things seem fine now! Or as fine as they could be. This will wear off soon, in any case.