Gaius. He killed himself on a crit by Chrom so I never got to talk to him and couldn't be bothered to reset. Made sure to save him in each playthrough after that. Otherwise I always reset when someone died, even if it was someone I never planned on using again.
90% of the posters will have Virion on their list. Poor Virion, youre just too pretty for the battlefield :(
Seriously? All you have to do is pair him up with Sully and keep him away from battle.
There's part of the problem right there, nobody with a sense of taste does Virion x Sully unless they're still in the early levels.
...Anyway, yes, pairing Virion up with enhance his survivability, but he's still in trouble if he gets caught with his pants down when he switches in to snipe something. I don't think I've yet to save Virion all the way until the last level in any of my playthroughs, though I have gotten him all the way to the spotpass paralogues once and he was pretty fantastic.