The innocent act that Natasha was putting on didn't fool Steve for a second, though he had to admit that her control over her expressions was masterful. She was unquestionably a far better liar than Steve was (which probably wasn't a fair comparison, since Steve was essentially constitutionally incapable of looking anyone in the eye and telling them anything but the honest truth), and knowing that, Steve made it a point not to trust any claim that fell from her lips, no matter how much sincerity reflected in her eyes.
So, no, she wasn't fooling him, but the condescension in her tone was more than enough to make his temper flare. It wasn't that he couldn't handle someone being mean; it was that this felt like a particularly cruel form of bullying. Steve had spent his entire childhood being laughed at, and it was easy enough to tell that she was winding him up for her own amusement. It was a miserable reminder of just how much he hated it here, how much he loathed nearly everyone in this room.
"There isn't a damn thing here to enjoy," he shot back, voice low and furious. "Not if I want to wake up tomorrow morning and still be able to look at myself in the mirror."
Because twenty-three children were dead, and this party was being thrown in celebration of the fact. And maybe it wasn't fair to direct his anger toward Natasha, who was much a victim as any other Victor, except that she'd allowed herself to be turned into the Capitol's poster girl. She was complicit, and more than that, she and people like her were the reason the Capitol still maintained an ironclad control over the rest of Panem. So long as everyone went along like good little puppets, refusing to rock the boat, then the Capitol was free to let as many people starve to death as they wished.
Steve had tried, he'd tried so damn hard to spark a change, but he alone had not been enough. He'd learned that lesson quickly enough, and it was Erskine who had paid the price. One person wasn't going to shift the tide, but a group of them together might, and in the end, Steve had decided to wait for an opportunity, however sour his own inaction sat in his stomach.
Keeping to the corner with a boring plate of food was maybe a pathetic form of resistance, but it at least lessened the likelihood of one of the many cameras in the room capturing him on film. It at least meant that the people in his district wouldn't see him smiling and laughing and dancing, gorging himself on indulgent treats and acting as if the Games were anything other than a brutal massacre of innocent children.