Sirius
Fear coiled itself deep in the pit of his stomach, Sirius felt it the moment they were in the air, that paralyzing fear that the Dementors brought with them. Only this time he wasn't rendered completely useless - the potions his brother had been working on seeming to actually help him and he was able to push past it, to focus on the fight to lead his group the way he was supposed to.
He was thankful for the dragons though, watching as they burnt up any of the Dementors that crossed their path. And Sirius actually thought he'd make it through this unscathed. He could fight - and he enjoyed doing it - and he was good on a broom, and as unhindered as he was from the Dementors he felt pretty good about the outcome for the day.
Of course, by this point in his life Sirius really should have known better than to start feeling cocky in the midst of a battle, things always went wrong at that point. He'd been dodging curses and hexes since they got in the air - but as he dodged one he ended up right in the path of another, the hex landing hard, hard enough to knock the wind right out of him and that brief moment was enough to rattle the control Sirius had been holding on to and he tensed up, only for a moment, but it was enough to make him lose his grip on his broom and go tumbling down to the ground, hitting hard, the world going dark mere moments later.