This should have been an easy win; he stood over Steve, he was the tender, he was still fully dressed, but that firm hand drew out a reedy whine from the back of Tony's throat, alarmingly needy and sad to his own ears, clear and unhindered with his mouth open and begging. Work through it, easy win. He pushed forward, forceful, wet, head tilting, deeper, like he wanted to taste all of him at once. His hand jumped from Steve's shoulder to his cheek, fingers curling around his ear, through his short hair, trying for purchase. He knew this taste and his lips and this heat, but he didn't know them like this, and he groaned.
It was the noise that slammed him back into himself, and tearing himself away took three tries; each time lurching forward again when his lingering tongue toughed Steve's or his lip or he just caught a shaky breath and he thought, just one more second. On the third try he pushed his thumb between them, hard against Steve's lips, pressed insistently by his own with his knuckles going white where they held at Steve's hip to control a shiver to a sporadic twitch.
"You don't want this," he declared, where 'you' was actually 'I', as in, 'I as you', as in, 'I with a clearer perspective than you for your own good'. 'I as you', Tony as Steve, knew he didn't want this because what Tony and Steve had, and what Steve was, was purer and far more dignified than what Tony was, and it (Steve, Tony and Steve, this) didn't need to be dirtied by Tony's insistent flaws. 'I as you', Tony as Steve, as in Tony, knew this because he spent more than enough time ruminating on Steve's perfection, his own toxicity, and the perfect balance of their relationship.