If you really want to make a character bitter, try CC'ing them on the creative notes.

Ever wonder how a show you love can suddently turn incredibly crappy? A Twitter feed called @TvNetworkNotes may help answer that question. Granted, there are a lot of moving parts to every TV show. Terrible creative decisions can come from writers, producers, actors - hell, even advertisors can get involved if they're dropping enough coin. But as the saying goes, "shit runs downhill." And in the world of television, the source of Shit River is usually a reservoir located on a giant desk in a corner office.

Sources: @TVNetworkNotes on Twitter