Gabriel in the book is a man who has many feminine characteristics. He is kind, nuturing and gets stuck with three gym classes that the school seems unable to fix. He’s stuck with a lot he didn’t choose and he makes do. You feel for him. Even when you know that he knows what he’s getting himself into, you still feel for him and so do the other characters in the book. Adam on the other hand is a man's man. He's smart and he knows it. He's talented and he knows it. He's hot and he knows that girls dig him and will do ridiculous things to be near him. He's pretty much given license to do what he wants and he takes it. Flan doesn't really fit into his world, but he doesn't seem to mind the attention.
In comparison, Aggressive, little Flan keeps getting caught with her hand in the cookie jar. And regardless of the circumstances, she’s always painted the villain. (Although, at one point, the paint is deserved. Sort of.) Even when she observes/is victimized things that deserve to be brought to light, she's kind of painted in a corner with no options.
If you’ve not read this book, You should. Daniel Handler is a genius who explores themes and issues in a way that is both thought provoking and entertaining. His work is cool. Its just freaking cool.