Tools of Characterization
Characterization in The Sixth Sense
Actions
You know the drill: characters who do bad things seem bad, and characters who are nice seem cool. For example, we know that Malcolm is a nice guy because he has devoted his life to trying to help kids, and he feels really guilty when he realizes that he failed one of them big time.
Need another example? Tommy, Cole's punk "friend," shows his true colors in how he treats other kids. He brags about his experience as an "actor" in a cough syrup commercial to all the other kids, which is pretty obnoxious. He and Darren lock Cole in a crawl space to scare him. That's definitely not something a nice kid would do.
We don't have to doubt Lynn's devotion to Cole for a second, because every thing she does is aimed at protecting him and trying to communicate with him. She does her fair share of yelling at him, but in this case, actions speak louder than words.
Family Life
Cole and Malcolm both display key details about their characters in their family interactions. Cole, for example, will do pretty much anything to prevent his mother from finding out about the whole "seeing dead people" thing.
Sure, that's partially for him—he doesn't want her to think he's a freak—but he also wants to protect her from the scary stuff he experiences and knows. He's a good son, and his protectiveness of his mom tells us a lot about where his priorities and character strengths are. He sees how hard she works and how helpless she feels to help him.
Malcolm, too, tells us a lot about himself when he tries (and fails) to put his wife ahead of other things. According to Anna, he's always put work first in order to help other people's children, to the point where she felt like she came second sometimes. Malcolm spends the whole film trying and failing to reconnect with her while also trying to help Cole; he often feels like the balance isn't working.
Of course, we later find out it's not working because he's actually dead, but let's just forget about that for a second. The important thing here is that he really wants to improve things with Anna. But he is also, at the end of the day, unable to give up helping Cole even when he thinks it's ruining his marriage.
Malcolm loses points in the husband department, but then he gains some back with his commitment to saving kids.
Speech and Dialogue
Dialogue also tells us buckets about the characters themselves in The Sixth Sense. Case in point: Cole in his altercation with his teacher, Mr. Cunningham.
We know from Cole's family life and his actions in general that he's a nice kid, but his dialogue with "Stuttering Stanley" shows us a different side of him. When Cunningham is staring at him in a way he doesn't like, Cole accesses some knowledge from his spirit friends and starts calling the teacher by a childhood nickname that was apparently used to tease him.
We're not saying that this makes Cole a bad person by any means, but it shows us how angry he gets when he thinks people are judging him.
Malcolm's dialogue with Cole screams "therapist." He's gentle, interested but not intrusive, and supportive. He knows Cole has a secret but doesn't push him too hard to share it. We can see why he got that award.