It's not like he's not grateful..
Fuchi may be a bit uncomfortable and fake near Tobi, but he is thankful that the other pulled him out of the prison. ...yet their relationship.. really was not so nice.
Tobi is just too.. scary. He is stoic, he is weirdly strong, his expression is mostly annoyed or unreadable, he never even smiles, he probably even thinks that Sunao is an 'awkward, helpless, useless guy that is just too stupid to take care of himself, how pitiful he is'. Oh... The mere thought makes him shudder and let out an annoyed sigh. Well, what else should he expect? He was avoiding meeting the apathetic other, he was trying to escape any encounter. Yet.. over his sleepwalking, his frustrating insomnia, and weird actions.... he couldn't escape it.
After Tobi pulled Fuchi out of the prison, things were rather tense. It is hard to get along. Yet somehow he feels as if he wants to... ew, he has to remind himself he doesn't deserve that and Otogiri probably sees him like nothing but a pathetic bastard. Maybe he is just starved for connection over these years, but he shouldn't let himself be this selfish. He hates himself.
Another morning. ...another morning. He still wishes he weren't alive, but now he can't really even attempt anymore. So he just has to push it down until the opportunity. He already said 'good morning, Monika!' with a trained smile to the girl Otogiri works with.
now as he walks past... he doesn't even want to fake his smile. He won't.
"Good morning, Tobi-kun."
his expression is awkward and a bit unreadable. It's always like this, almost. It is so embarrassing! he is such an awkward person, so annoying, no wonder the other sees him as creepy. He fights the urge to facepalm at his own stupidity, instead looking away and bearing with his thoughts.