Have Harry somehow sent into the 40K Universe, I am thinking by an Eldar Farseer, and he is raised by the Inquisitors.

When he arrives in the 40K universe, maybe he is about 6 or 7, and he lands on a planet where the Black Ship has just landed.

He is brought up to use his magic in the name of Him-On-Earth, and is taught to use his magic through incantations in the Heiratic(sp) language, and he uses them in different ways commonly seen in Psycers(sp). But he is NOT to be over powered. He isn't to have all the possible powers in the 40K universe. Just give him a few, like maybe a lightning blast, a mind blast, and mind readings. As well as training in creating diferent types of auras with his power (ie auras of protectiveness, invisibility, silence, etc).

He starts to serve this Inquisition in whichever Ordo you wish, and lives a fairly good life as an Inquisitor for many years. He then gets attacked by a demon, and is killed by it. However, in a last ditch effort to save his soul form eternal anslavement to demons, he sends his soul hurling from his body in the instinctive direction of "home", which turns out to be his home universe, but in another reality, where his soul lands in that worlds resident Harry Potter, at a time of your choosing.

There are benefits of having him land in an older Harry (perhaps when Harry is possessed by Voldie in the Department of Mysteries, the soul lands in him and frees him) and also benefits in him landing in a younger Harry (the image of Harry running seeing Hagrid for the first time and shouting "DEATH TO THE IMPURE" or soemthing similar comes to mind)

Harry is not to go Evil, or become a badass punk type person. In his life as an Inquisitor he became a hardened simplist. He doesn't live for luxuries of any kind, and he will do exactly what is needed to solve a situation, no matter what the extraneous circumstances may be.

Dumbledore can be with or against him, but Harry isn't going to try and hide what he is from people. he isn't going try and manipulate dumbledore into thinking he is niave or anything.

How he actually acts at Hogwarts I leave up to you.

Characters that are to have no major part in the fic:

Ginny Weasley, isn't to play ANY major part, as in no having him fall head over heels in love with her, but also no having him spend chapters upon chapter plotting to kill her.

Ron Weasey, Harry feels that he isn't intelligent enough or powerful enough to become a major player and therefore isn't worth his attention.

That is it, I think that he would try to get together with both Hermione and Malfoy ( not in any sexual snese) because of her brains and his political muscle.

I think I have covered all major points, please ask clarification at any point you want.