Concepts
I have a couple of character concepts floating around in my head that I've never really gotten the chance to use properly, and it kind of annoys me. They don't go away until I do something with them, and they're just not amenable to coherent fiction--the little snippets that happen when a character gets to me don't count as useful.
The crow cop is pretty setting-specific; she only works in the nWoD Changeling. The trying to be a good cop in a bad world trope could be worked into almost any modern setting, I guess, but at this point my mental picture is so bound up in the way she cocks her head and looks at people sideways, I don't know as it can be teased out.
Meanwhile, I've been watching House again and, aside from the fact that Hugh Laurie is sexy, I just love the character. There's so much you can do with all that: genius, great at analyzing the behavior of anyone he doesn't care about, constant pain, lack of control over it, a total asshole until suddenly he's being kind under cover of snarkness. It's just fabulous. The problem with a House derivative as a PC, though, is that it would be of a kind that's tough to work into a group: amazingly annoying but with qualities that make it worth keeping around. Not all the other players are going to be down with that, and it's also tough to make sure that such a character doesn't take over the entire game.
Then there are the characters who just never got where I was trying to take them, generally because the game crashed and burned before I could get there: Annis, Tanith, Astrid, Octavia. Astrid wasn't so bad, because I never got to the "writing bits of random fiction" stage with her (in large part because I was a Marvel-shaped peg trying to go into the GM's DC-shaped holes). But I really wanted to see what I could do with the other three.