I've always had a little bit of a hard time pinning down what it is I like in a character, since there's so many things I like and so many variations of those likes. But it wasn't until recently that I discovered there's a character type - a solid character type - that I absotluely do not like. And that's the rebellious hot-head. These are usually the characters that are usually part of a group or partnership but decide to go their own way, do their own thing, do things their own way, and to heck with everyone and the consequences. They're also the character that in their "do their own thing their own way" quest end up getting not only themselves but everyone else in a crap load of trouble.
Don't get me wrong, I do love me someone who doesn't take crap from anyone. But there's not taking crap from someone, and then there's being so focused on not taking crap from anyone that the character also doesn't take anyone else into consideration, only their own needs. They don't listen to those they profess to care about, and when the consequences hit those they profess to care about, they don't seem to really care. And that makes them irritating as all heck.
However, when it comes to this hot-headed, rebellious characterization being used as a learning curve to provide some character developement, I'm all for it. The character still irritates me, but usually over time, once the character begins learning valuable lessons as to why it doesn't pay to ignore the consequences, I end up really liking them. It's when this characterization is there to make the character look cool or BAMF, with little to no learning curve, that I end up really disliking them.
A good example of this the character of Niska from Humans (very minor spoilers ahead). If you don't watch Humans, Niska is a female synth (robot) capable of feeling human emotions. Her characterization is very much that of the rebellious hot-head, and it's her character that made me realize how much I dislike this character type. She's decided to go her own way, but thus far her actions have been wracking up some really bad consequences, not only drawing the wrong kind of attention to herself but to her family of fellow feeling synths and one half-synth, half-human. What sealed my dislike for her was one scene in which she pretty much bashes Leo - the half-human/synth, who's been trying his best to look out for his family of synths - by implying that he's been doing a crappy job of protecting them thus far, and that she's better off going it alone. Except little miss Going-it-Alone has not only killed one man but nearly killed another, and is basically, as I said, drawing all kinds of attentiont to herself as well as Leo and the other feeling-synth, Max. She's causing more problems than she's avoiding and it's frustrating. I do't care what she's been through, I don't care what she's going through, because her experiences does not excuse her putting not only herself in danger but the others as well.
In fact, I beleive Rocket Racoon from GotG summed it up nicely as to why I really dislike these kinds of characters: "Everybody's got dead people! But it makes no excuse to letting everyone else around get killed along the way!"
Again, I'm all for characters who don't take crap from anyone. I'm all for characters who sometimes cave to their emotions and do stupid things now and then. What I'm not for are characters who do stupid things constantly and don't care who it ends up hurting. I'm a sucker for characters who learn from their mistakes, not characters who keep making more mistakes because their life was hard and to heck with everyone else.
(And what kind of sucks is that Niska seems to be the popular character when all I want to do is throttle her. Who knows, maybe I'll come to like her later on, but for now she really gets on my nerves).
(Leo, on the other hand, represents a lot of what I like in a character - doing everything possible for family and friends, more concerned with others than with the self. Tries hard to be cautious and do what's right even though he mostly fails at it, and so on. But most of all, tries to consider the friggin consequences. He gets things wrong more often than right but at least he's trying. Niska just doesn't really care anymore.)