Broken Chains by Darth Marrs
https://www.fanfiction.net/s/7718942/1/Broken-Chains
This is not a usual recommendation because this is a very dark story and normally those are good but not worth rereading. This breaks that pattern in that is both excellent and chilling. Remus is unable to stop Harry from going after Sirius into the veil. He continues to come to the veil everyday for a month just hoping. Then Harry gets thrown back out of the veil and the world is changed forever. When he awakes he is no longer Harry Potter he is the Darth Shaddix, Dark Lord of The Sith. Hermione finds that the only person he cannot attack is her and realizes that it means Harry is still in there. Then Dumbledore once again proving that his arrogance know no bounds attempts to break the mental block to separate the memories. It does not go well and what is left is someone who is a blend of Sith and Champion. He intends to remake the world and with Hermione and Luna (as a seer) at his side stands a good chance of succeeding. There is torture, rape, blood shed, dub con and in some cases gratuitous violence. He is not the Harry Potter they knew he is something else. The characterization is amazingly done, the characters make choices that while not canon fit what they have become. This is not suitable for young readers and is rated M for the torture, rape and the explicit sex scenes. But if you can handle that it is a wild ride, a very believable story and the perspectives change enough for you to see the worlds reaction to the New Savior.
