With all the Manipulative!Dumbledore stories floating around, I've came up with an idea. Instead of simply having him as a person who makes roads to hell due to good intentions, why not make him a person who purposely paves a highway to hell all to further his ideals? In fact make him a Dark Lord that has existed for a long time by possessing other people, or even better, THE Dark Lord spoken of in Trelawney's prophesy! After all, it isn't specified WHICH Dark Lord, and besides, "You-Know-Who" is too vague of a title to specify a specific person.
Now in order to mark Harry as his equal, we could make Dumbledore a bit like Orochimaru by making him view Harry as a potential vessel to possess. After his "death", as per his plans, Dumbledore's portrait in the Headmaster's office, which in actuality is a Horcrux. However, he underestimates Harry's willpower, and in an amazing show of willpower and magic, Harry manages to throw off the possession attempt, and as a result gained the knowledge and power contained in that shard of soul, which is quite a bit, since Dumbledore put most of his investments into this piece. However, not all of Dumbledore is gone, as he had a contingency plan in place in case things goes wrong. Cue the takeover of <insert name>, preferably somebody that Harry trusts. However, this part of Dumbledore only knows how to gain power, and how to reclaim what was rightfully his, and so is not as powerful, only more cunning and ruthless.
For an extra bit of twist, make ol' Tommy-boy one of the past potential candidates for Dumbledore to possess, only in the process of making him the ideal vessel, he became a corrupted and lesser version of what Dumbledore actually is. On a subconscious level, Tom fears Dumbledore because he knows he is merely a lesser copy, which is why he delved into the Dark Arts in the first place.
Now in order to mark Harry as his equal, we could make Dumbledore a bit like Orochimaru by making him view Harry as a potential vessel to possess. After his "death", as per his plans, Dumbledore's portrait in the Headmaster's office, which in actuality is a Horcrux. However, he underestimates Harry's willpower, and in an amazing show of willpower and magic, Harry manages to throw off the possession attempt, and as a result gained the knowledge and power contained in that shard of soul, which is quite a bit, since Dumbledore put most of his investments into this piece. However, not all of Dumbledore is gone, as he had a contingency plan in place in case things goes wrong. Cue the takeover of <insert name>, preferably somebody that Harry trusts. However, this part of Dumbledore only knows how to gain power, and how to reclaim what was rightfully his, and so is not as powerful, only more cunning and ruthless.
For an extra bit of twist, make ol' Tommy-boy one of the past potential candidates for Dumbledore to possess, only in the process of making him the ideal vessel, he became a corrupted and lesser version of what Dumbledore actually is. On a subconscious level, Tom fears Dumbledore because he knows he is merely a lesser copy, which is why he delved into the Dark Arts in the first place.