Maglor did not aimless wander the shores of Middle Earth after the War of Wrath, as hypothesised by Pengolođ. The story of what really happened after Maglor and Maedhros reclaimed the Silmarils.
Harry's twin Daniel is the BWL. Harry was given to the Dursleys after Hallow's Eve, he didn't quite make it there. Not LOTR crossover. Rated T for now. No pairings yet.
Harry Potter is not a Warrior of the Light, instead, he is his own man. He will do anything to achieve his goal. HHr Manipulative!Dumbledore Bashing!Weasley&Weasley
The Potter didn't die cos Moldyvort died before he had a chance to murder them dead. I don't know about the relationships yet but I'll decide on that as I go. I'm going to go along with the story, but definitely HHr.
Harry was adopted by the Grangers on the night of his parent's doom. The Grangers really doesn't make too much difference to the plot other than the fact that Harry was not abused.