It's hard to see his eyes, downcast as they are, but they do look upwards- slightly. And there's a short little hnh to go with the motion, but there's only the slightest of resistance to go with Tadashi's gentle tug.

Robert's not smiling. He looks tired. And he doesn't say anything for a few moments, because short of reiterating how confused he is as to why Tadashi's still here - what is there to say?

"...it wasn't supposed to be like this."

Other than a murmur that sounds childish even to his own ears.