Wraithbait

But their most terrible failures were yet to come, and they would each face losing everything, including themselves.

(Please note there is a warning for non-consensual sex in the story, but that there is no violence involved.)

Sheppard was a Charmer, one of the feared ones, whose particular Gift let him create faith whenever he needed to be trusted or believed. But Sheppard didn't trust himself not to destroy what he loved most. And somewhere along the line, amid the terror and chaos of the Expedition's first year in the Pegasus Galaxy, what Sheppard loved most had become Rodney McKay.

McKay didn't trust anyone. As soon as you started trusting people, you started counting on them, depending on them, and that was when you became vulnerable. And vulnerable things didn't survive. So just when, exactly, had he started trusting Sheppard?

And what was going to happen, now that he did?