Something in Harry changes that summer between fourth and fifth year. At his trial he discovers what someone has been hiding from him since he was born.
Fangs of Death face the Power of Life. This is what happens
Halfway through his fourth year Harry wakes up to a surprise.
smut with plot, harry finds out that all but a few of his 'friends' have been less than faithful to him so now he's "mad as hell and isn't going to take it any more!"