Fyrexuss

Ex-Blue Lantern, whom, after a war on their planet caused the whole thing to be eradicated into a lifeless rock while he was gone on an unrelated mission, was so grief-stricken and mad at themself for not being able to do anthing, became a red lantern . They had a lover, friends, sanity, and that all went down the drain as anger and grief took them over. 

Atrocitus still hasn't given them their mind back due to the chance that they might actually break down over everything that's happened to them. Berazer-kerr is currently their team-mate to avoid them getting too out of control despite being completely taken over by rage.