This also applies to Downton Abbey's Thomas Barrow. I wanted to like him and I thought his petty vindictive ways were somehow understandable considering being gay during a time when that could land you in jail was pretty shitty and the way he was so unlucky with his love interests was kind of tragic (especially in season 2). But when every little bit of character development he got kept getting retconned and he kept doing stupid shit that backfired over and over again I lost all sympathy for him and now he's just plain annoying.