A/N: As a side note, I don't care who exactly is doing the fucking and who is taking, honestly, the girls could wear a strap-on and it wouldn't make a difference to me, in fact, that may be kinda hot... (¬‿¬)
Relationship(s) that may apply:
Harry Potter/Tom Riddle | Voldemort
Harry Potter/Tom Riddle |Voldemort/Lucius Malfoy
Harry Potter/Lucius Malfoy
Tom Riddle | Voldemort/Lucius Malfoy
Lily Potter née Evans/Severus Snape
Harry Potter & Severus Snape
Harry Potter & Lily Potter née Evans
This would be a mostly politically oriented fic with a lot of time in a courtroom but it would also have the potential for behind the scenes action with terrorist groups. Harry becomes Lord Gryffindor and uses this power to help settle the conflict plaguing Britain's Magical Community. I see Harry as a Master of Death Harry who was reborn in another reality, much like his own, because it is both a way for Harry to be knowledgeable beyond his physical age and mentally strong enough to be able to make hard decisions when required; it allows Harry to know Voldemort in ways he wouldn't have access to if he wasn't what he is.
A Master of Death Harry Potter is reborn in the past (when he was born; July 31st, 1980) in an alternate version of the world, everything is the same until it gets to the time of Voldemort. In this version of reality, Voldemort isn't a complete psycho; he's sane and pushing against Dumbledore for power, it's still dark vs light but things are kept more political, of course, there are some small radical groups and one such group commits terrorist attacks and they end up blowing up something, possibly the Auror offices, and James and Lily Potter and Frank Longbottom are caught in the magical explosion along with a few unnamed others.
The properties are something that infects the magical core and has no known cure. Harry finds the cure (and hunts down the terrorists responsible at some point) but one of the properties in the cure causes memory loss as a side effect. James and Frank were in too critical of a condition and die. Lily survives but without most of her memory as she was far too close to the detonation zone. A mind healer comes in but because of her condition he couldn't save as much of her mind as many of the others were not affected as greatly, except for one other who was also too close to the blast so they also have only partial memory.
Harry becomes the head of the family but ends up as the Gryffindor Lord because he wants on the council and this proves their blood isn't muggle as many started to suspect due to how common a muggle name Potter is. In this universe, those born of a pureblood and muggle-born are still considered pureblood instead of half-blood because of the magical bloodline. The ancestor who married the Peverell Lady was really a Gryffindor but hid that fact so he could live without things being crazy; he wanted the simple life.
Harry invites Snape to see his mother whenever he wants as he is the only person Lily remembers being very close to within the magical world and he totally becomes Daddy Snape.
Harry restores a Castle and verbally guts Dumbledore on a regular basis.
I like the idea of making Hadrian his real name so Harry can be his nickname (but mostly because Lord Harry Gryffindor just sounds wrong to me for some reason).
Harry also didn't go to school; Harry tested for the OWLs and the NEWTs at a young age (possibly eleven in order to legitimately get out of going to Hogwarts) and passes.
Harry regularly travels the world, first with his parents then by himself as he ages, picking up masteries for different magical fields of study along the way.
Harry has a habit of doing other things while at council meetings with the other Lords such as reading or doing his paperwork. People learned not to talk down to him very quickly when the first person said something insulting to him; probably about his age and how if Harry wasn't going to take things seriously, he should get out. Every time someone says something stupid or when things get somewhat interesting during the discussion (for whatever all the Lords were called in for) Harry will start to pay attention more and will look up and start to watch the proceedings and will even close his book or put away his paperwork altogether when he feels it is required, like when whatever the others are saying are horribly wrong, like some fact about law they bring up in debates is completely untrue; another reason Harry could choose to pay attention is when he needs to verbally castrate someone who has annoyed him enough such as by being a prejudiced jackass. Harry quickly becomes known for his quirks while in the courtroom and those who generally agree with his points find watching him discuss issues turns into something they look forward to, to the point that they start to enjoy going to these meetings again.
The blood trait of a Gryffindor is to morph into a griffin; Lion-like creature but with wings like an eagle (I took some creative liberties on what a Griffin looks like because I wanted it to tie in with the House crest, a lion, more).
Harry could find a vault in the Gryffindor Castle that has the family riches in it and one section contains a dowry that was certainly for the Slytherin family so Harry asks Voldemort if he wants to come see them and take what he wants. I picture him bringing Lucius Malfoy as a witness because what Slytherin would go to a Gryffindor's home without backup? While they are there they see Snape out in the garden with Lily.