Recently, there's been a spat of fun chatter on the IGDA forums about what kinds of emotions we should be portraying in games besides, say, an adrenaline rush.
We are definitely seeing a growing number of games trying to touch the player with more than a zortch-kafwoom. From ICO to The Sims and even Leisure Suit Larry, we are seeing games slowly pull away from violence.
Violence will never be gone from games, of course. The day nobody is playing a violent game is the day I release one just to make fat sacks of cash. But like movies, violence is not the only thing games are about any more.
I'm of the opinion that "love" is one of the things we need in games. By "love" I don't mean the fuzzy greeting-card kind of love. Sure, we can have some of that, but when I say "love", I mean "dedication and obsession".
Most of the most fascinating characters in video games (and in movies and comics and books) are fascinating because of what they love - or what they cannot love. Especially villains, because obsessions tend to make a character rather opaque, and good guys are usually window characters.
Think about your favorite characters:
Darth Vader was about his tortured obsessions and dedications.
People liked "Angel" from Buffy because for the same reason. Hell, people liked Buffy herself for how she dealt with her new duties and her forming dedication to them.
All of Clint Eastwood's characters were about their dedication - or obsession - with the life of the gun.
Hannibal Lector's fleshy obsessions and his bizarre dedication to politeness.
Think about it. Most of the really cool characters have bizarre obsessions. The mad scientist who builds a robot in the shape of his dead daughter. The dedicated starship captain. The giant moster who defends Japan.
This is probably because obsession is pleasantly bizarre without comprimizing the humanity of the subject. For example, a movie about someone with tourettes would almost certainly have to be about showing that the person is still a person, even though he curses continually. On the other hand, a movie about someone who loves someone with tourettes is far more accessable, because that person is inherently interesting without seeming incomprehensible.
At least, that's what I think.
So, in summary: most characters can be defined by their obsessions - what they are dedicated to. Even characters which are not obsessed when they start generally become obsessed by halfway through the story.
That's one of the things which makes characters interesting. It operates on a deep level, so you'll want to do other things that make a character interesting on the surface, but don't forget obsessions. Dedicate yourself to them. :)