[Bucky may be good at holding back his anger from his voice, but Steve isn't. He's never been good at holding back his temper. It's gotta get out somewhere, even if it's just a little spike of wounded pride. So he stops where he's standing to give Bucky a stern look.]

Okay, first off - it's called empathy. You aren't a charity case, I've never pitied anyone in my life. Don't insult me.

[After that he manages to reign it in. Yes, he's angry that apparently that's what Bucky thought his motives were, but... but maybe people have done that with him before. Maybe he has reason to assume that's the motivation. Don't be an asshole, Steve. You know for a fact everyone has their own struggles, their own battles in their day to day life that no one else knows anything about. Deep breath, exhale, back to calm.]

... Just because you're the only vet in this class doesn't mean you're the only one I've ever dealt with. In the class before the one you're in there were three, and on the class on another day of the week it's all vets aside from one other person. Sure it's what prompted me to volunteer at the center but it's not the only thing that motivates every single aspect of my life. Aside from my friends group from college I haven't invited anyone else home to make dinner for them before, veterans or not.