I think that there are a fair amount of people sitting around with little sheets about their characters, either literally or in their head, that say “Edwin’s flaws are x, y, and z, and Edwin’s positive traits are a, b, and c.”
Every time they write Edwin in the story, they give Edwin bad consequences when he does x, y, and z. On the flip-side, when he needs to get out of trouble, he can always rely on a, b, and c.
This doesn’t have to be the case, though. I have a character who has a lot of perseverance. This seems like a good trait, and it helps him a lot in several situations, but when he learns that his brother took a different lifestyle than him, he bugs his brother every day for years. This positive trait causes his life to go downhill during this time.
Most flaws can sometimes be used in a good way, or at least have good consequences. Most positive traits can sometimes be used in a bad way, or at least have bad consequences. If you take it far enough, you get characters with no positive or negative traits, just traits that sometimes work for them and sometimes don’t. I see this as the ideal, but certain traits are hard to portray the opposite way.
The power of changing traits from negative to positive can be used wrongly, of course. If that’s all you do with them and never portray them as negative at all, you end up with a Mary Sue.
Don’t have it rigid in your mind, “This is a flaw. Something bad happens when Edwin does this.” Instead go, “This is a mostly negative trait. Usually something bad happens when Edwin does this, but occasionally it works out for him, and this is balanced by the times his positive traits get him in trouble.”
The follower of the day is ampauthoress.