Sorry, Charlie

Desmond spends a lot of season three trying to prevent Charlie from dying. When they find Naomi, soon after Mikhail drops in. Des says he'll let Mikhail go if he saves Naomi, and is good on his word.

Charlie isn't pleased. He figured the only good Other is a dead Other. When I first saw this, I didn't realize, but he's right. Because they let him go, Mikhail comes back and takes out Charlie. Still, after all Des has done to prevent this, he probably doesn't feel guilty. It was gonna happen sooner or later, anyway.