Defecting with the prisoner - Poe Dameron, he killed Slip, he killed so many other stormtroopers but he's against the First Order and he's a pilot and SN-2187 can't fly worth a damn, and she needs to get out, knows they're going to crack down on her for refusing to fire on the villagers, knows she's been walking a thin line - knows she'll suffocate if she spends one more second in that damn bucket helmet -

It's a bit of an impulse, but in the same way gasping for air's an impulse when you're drowning.

She snaps her designation at him when he takes time off from piloting the ship to start talking - does he ever shut up - she barely catches him saying he'll call her Sunn -

Then he decides to go back to Jakku. Never mind that'll get them caught, they need to get out of here, SN-2187 can vividly picture what'll happen if they get caught and there's almost no way off Jakku if they have to abandon the fighter which they probably will...

She's distracted enough arguing with him that her concentration slips. Stupid. Shots get through her defense. Extra stupid. They're going to crash. Why can't I do anything but mess up.

Poe tells her how to eject.

His seat doesn't follow her out, not that she sees.

She falls down to the sand, hits hard, and passes out.