Character #1 Ron Weasley, from the Harry Potter series.
WARNING
CONTAINS SPOILERS.
First, I would like to say that I do not like Ron in books 4-7. And that I would not choose to analyze him, myself. Now, on to the analysis.
1. Let's start from the beginning. 'Why would Ron befriend Harry?' Maybe because Harry shared candy with him, or maybe because he was the Harry Potter. But I think that it would take more than that to start the sort of friendship they had. Because probably Harry knew enough to tell which 'friendly' people were there for fame or a friend, like when Harry turns down Draco Malfoy's offer of friendship which would undoubtedly have turned the whole series into disarray, and lead Harry down the path to the same future as Voldemort. This question I haven't answered for myself yet, but I think Harry befriended Ron because Ron didn't scorn his lack of intelligence of the wizard world, and Ron befriended Harry because Harry didn't scorn Ron's dry sandwich, or big, poor, family.
2. 'Why did he follow Harry into trouble, and behind the trapdoor?' I think by that point in their friendship they would stick together through thick and thin. And this is proved when Ron lets the queen get him to win the game of chess, and allow the other two to cross to the other side.
3. 'Why stick with Harry even when the school thought he was the heir of Slytherin?' I think the answer to that is the same as the answer to the second one, but also because Harry would have done the same for him.
4. This is a point not a question. By #3 Ron, Harry, and Hermione have developed a friendship for life.
5. 'Why does Ron continue to follow Harry into trouble, when he knows what's going on and it puts him out of the good graces of his mother?' I think that in part Ron knew why Harry did it and he agreed with the intentions.
6. 'Why did Ron get so angry at Harry when Harry was entered in the triwizard tournament in #4?' One, Ron thought that Harry had found a way to enter a name and get in. He was angry that Harry, who he thought to be a friend who would share that sort of thing with other friends (he was), apparently hadn't. Two, Ron was getting tired of Harry being famous, and being around famous Harry without getting any attention himself, and he thought that Harry sought for the attention and tried to bask in it without Ron.
7. 'Why did Ron get mushy with Lavender Brown?' This is one of the most disappointing things a character I know about ever did. I think that Lavender liked him because he was getting more and more credit for Gryffindor's quidditch team winning so many games and she was that kind of person, and he liked her because he was getting to that time in life and Hermione was not that kind of person.
8. 'Why did Ron leave Harry and Hermione in the woods in #7?' This is another of the most disappointing things that any character ever did. First, Ron thought that Harry and Hermione were falling in love, that Hermione, instead of being in love with him, as he thought, was opting for the more famous guy. Second, Ron was giving up hope of ever finding the seven horcrucses after so many fails.
9. 'Why did Ron come back after he so decidedly went away?' This is not a hard question to answer. The book says that he regretted leaving as soon as he disapparated. And, probably, he had time at Bill's house to think about how he went back on his word, and left them there, he probably felt guilt and shame, and his unspoken accusation seemed unfounded. So, when the chance came, he took it.
I have tried to look at the big decisions he made and why through the series, and I would not like it to appear that I made any excuses.
If you have any questions, or topics you think left untouched, please comment them.