[Once Cain looks it over he will realize that yes it is indeed his actual hat, only there's simple purple fabric carefully put down onto the ... Visor part? So, that it isn't red at the moment but the purple fabric seems easily removable by hand. Also, amazingly, it doesn't have any horn holes in it, Eridan was able to get it on his head without too many problems.]
You should be. You should also be sorry, I made sure this was as close to the actual Commissar outfit you wear as possible! [To the point he stole the actual hat, without Cain even knowing that it was stolen. How...]