Strong Characters (Audience participation post!)

Although not strictly science- or space-based, this post has been kicking around my mind for a while. I decided that today (when my sinuses are trying to kill me and I don't quite have the energy to talk about exploding meteorites in Terra Nova), would be a good time to write it. And fair warning, I am going to Use Examples from Harry Potter, because JK Rowling not only provided good examples, but most of the world already knows what happened in the end so I don't feel bad about possible spoilers. Sorry to those three people in the developed world who haven't read Harry Potter. Well done.

Actually, it's not so much the blog post that's been rattling in my head so much as the question: what makes a strong character "strong"?

Several people have written all over the internet that "strong", when we're talking about characterisation, does not automatically imply physical strength (particularly relevant when we're talking about strong female characters, but that's not quite the point I want to raise today). I want to talk about emotional strength and skip the argument as to whether that's equal to physical strength.

Strong characters in Harry Potter.

It is easy to identify characters that lie at extreme ends of the emotional strength spectrum. The hero/ine who sacrifices a lot to save her friends/village/the world is almost certainly going to be a strong character because (assuming it's a good story) they are going to have various obstacles to overcome, both physical and emotional, perhaps stemming from their flaws. Antagonists in some ways have less stringent requirements. Voldemort won't allow anyone to stand in his way (making him strong, if Evil), but Wormtail spends his time attaching himself to strong people around him (first James and Sirius, later Voldemort). And I'm sure he's described as "snivelling" at least once; a clear indication of a weak character.

There are other situations when the distinctions between weak and strong are less cut and dried. There's the character who does the right thing for the wrong reasons or the character who does the wrong thing for the right reasons. There's Snape who did very difficult things for love and, ultimately fought on the side of Good. He didn't do it for noble reasons (in my opinion) like the lead trio, but he still had to be very strong to prevent Voldemort from catching on.

What about the character who is so strongly affected by something (a death, a breakup) that they have difficulty functioning? Are they stronger or weaker than the character who represses their emotions or (for whatever reason) doesn't feel anything? It seems clear to me that the character who is terribly saddened but still carries on through their hurt is emotionally strong. (Although, if you want to argue in the comments, knock yourselves out.) I ask you, which is "stronger": character A, who can't come to terms with the terminal illness of character C and avoids them because they hurt too much to see them suffer, or character B who isn't as emotionally affected but stays by character C out of a sense of duty? It's a grey area, although I'm sure character C would appreciate B more, especially from a practical point of view. (And character D who is heart-broken but stays around anyway would be the clear winner, but they aren't always an option.)

On the other hand, the character who isn't scared can't be brave.

What are your thoughts on the matter? What makes a strong character for you? What are some good examples of weak and strong characters in fiction?