Well, he desperately wants that Order of Merlin, and doesn't really care about the truth in order to get it, and he wants acknowledgement from Dumbledore for his contributions, wich is not a bad thing, per se, except that when he doesn't get it he resents the people who do.

I don't deny Snape's depth, but I just urgh. When people defend him, it makes me crazy, especially when they excuse or justify his treatment of the children.