Chris recognizes the engine room as soon as he walks in--How can he not? It's been in his dreams for nearly a decade now--but everything happens so quickly, he doesn't have time to do anything but what he's seen himself do ever since he reached out to the crystal. Once the first alarm sounds, there isn't any doubt or hesitation in his mind--even if he could have walked out before it all started, he wouldn't have. He does what the crystal has told him he'd do, which is, in its own way, a relief. A part of him has dreaded being put to the test and not living up to that vision, dreaded finding out that he's not the person who jumps to help no matter what, dreaded failing the kids under his watch by not being fast enough, strong enough, determined enough.
He can feel the effects of the Delta radiation blast starting to affect him even as he lunges for the last cadet. He gets her clear, but then stumbles, all the strength in his legs draining out more quickly than he could have imagined, as he tries to follow.
Oh my god, you are seriously too damn stubborn, he hears Tilly saying in his mind and it's her he's reaching for as his body shuts down and he loses consciousness.