Disclaimer: I don't own Harry Potter or Rise of the Guardians, because if I did I could prove that it wasn't real - WHICH IT IS!
Crossover: Rise of the Guardians/Harry Potter
Pairing: Jack Frost/Harry Potter (I'm not sure about Bromance or Romance, tell me in the comments)
Summary: In the Battle of Hogwarts, Harry dies but the Man in the Moon brings him back to life as Guardian of Life & Death. He is found by the other Guardians, and is not accepted easily because of the power he wealds. But, he has to help with Pitch Black, how else will they get Sandman back and restore Peace & Balance?
Here goes: Guardian of Life and Death.

The first thing Harry noticed after the killing curse hit him was the blinding whiteness that surrounded him. Was this what dying felt like? He'd had near-death experiences, but it didn't feel like this.
He found himself lying on a floor, of what looked like King's Cross Station. Ok, this is unexpected he thought. Harry pushed himself up, and noticed for the first time that he wasn't wearing his glasses, but he could see perfectly well… too well. He was dressed in a plain white robe which covered his feet. He jumped slightly at the sound of a voice – but the voice soothed him, and he felt its power wash over him like a rush of warm air.
"Hello, little one," the voice whispered,
"Who are you? What are you?"
"I am the Man on the Moon, the Guardian of the Guardians, if you will. You have suffered, and I grant you a new life. You are chosen to become Guardian of Life and Death – the Hallows themselves gave you this power."
Harry was confused. The Man on the Moon was real? And… there were Guardians?
"Who are these Guardians, and what does being one mean?"
The voice chuckled, and continued its explanation.
"You may have heard of these Guardians – North, Father of Christmas, Tooth Fairy, Easter Bunny, The Sandman, and The Boogeyman – Pitch Black. These are all Guardians of some sort. Being a Guardian means you are the physical being that makes what you Guard. You, as Guardian of Life and Death, will keep the balance and escort beings to the Other Side. If you disrupt the balance, the structure of the Universe crumbles, until all that it left is chaos. People die when they have to, not when you decide. Even if you hate them, they must die at the time they are….scheduled. The other Guardians will find out about you eventually, but hide from them before you make your presence known. Pitch Black, the Boogeyman, is making an uprising. He wants to bring his reign of terror over the world – and destroy all other Guardians. When the time comes, you must join the others to save the Universe."
Harry stepped back, over-whelmed by the amount of information he was pertaining. He mulled it over in his mind… Now he was dead, Voldemort could die. It was possible… He had nothing to lose – only days before the final battle, he'd walked in on a conversation with Mrs Weasley, Ron, Ginny, Hermione, and Dumbledore's portrait. Apparently they'd only wanted him for the money and fame. Harry had pretended to still be friends, but really he'd shut off his bank accounts, deleted all sign of marriage contracts, and generally stopped everything from happening. Maybe this deal wasn't as bad as it could have been – helping people be put to rest, allowing new beginners to start life. Immortality wouldn't be that bad, as long as he had someone to share it with. The Guardians.
"Ok, I'll do it." Harry managed. There was no going back now.