Disclaimer, If I owned Harry Potter I would never have brought Ron Weasley back into DH after he deserted the hero and heroine. Then again I would never have written those two awful books HBP or DH So I definitely am not JK Rowling.
"Come in," Albus Dumbledore called as he was finishing his end of year reports, he noticed someone's shadow fall across the desk as he continued writing "Sit down please I will be but a minute," he said without looking up. Dumbledore stopped writing instantly as he was hit by the strongest binding spell he had ever encountered, and that included his own. He struggled to raise his head or at least his eyes to see who had power enough the bind him, the greatest wizard alive. Slowly recognition of the voice that almost whispered "I would rather stand old man," settled into his mind.
A much younger man than Albus walked around Dumbledore's desk and with a deft flick of a wand the old wizard was disarmed, his wand placed into the back pocket of the tatty old jeans the young man wore. "Finite," a voice whispered in a short hiss. Dumbledore looked up at his assailant only to find he was looking into the eyes of Harry Potter. An older version of Harry Potter than the one he knew.
"Who are you?" the old wizard demanded of the man in front of him, I know you're not Harry Potter, you can't be. Harry is down there on the lawn with his friends Granger and Weasley.
Harry Potter walked around the old mans desk and looked down on the perfectly kept lawns in front of the castle, "You know old man you are quite right, I am down there with Hermione and that traitorous rat Weasley. Which reminds me I have an appointment with a certain red head, tell me old man what punishment do you think I should inflict on Weasley for stealing my fiancé? Do you think I should mete out the same punishment to him as I am about to mete out to you, for the way you have manipulated and totally ruined my entire life.
Dumbledore chuckled a sort of derisive sounding noise "Who ever you are your disguise will not work, you look at least fifteen or maybe twenty years to old to be Harry, you will not be able to get away with anything. So enough of this foolishness, who are you and what do you want?"
A pair of cold emerald green eyes glared at the old man for a second before they flared into green flames, " Revenge, Albus Dumbledore, I am your executioner, in a moment or two I am going to kill you for all the innocent lives you have caused to be lost due to your stupid meddling and manipulating," Harry Potter answered.
For the first time since the binding spell had been lifted from him Albus Dumbledore remembered the power behind it and he knew what fear was, it was then he said one of the most stupid things he could have said "All I did was for the greater good, surely you must see that."
Harry looked at the old man as though he had just realised he was crazy, "No, killing you is for the 'greater good' old man, for the greater good of all those innocents you needlessly sentenced to death with your manipulations just so that your plans for a wizarding world you designed would succeed. And for those souls you would add to your long list of deaths you have caused it's time to pay old man. Can you feel the pain in your chest, nasty isn't it. You know old man it's truly a shame I can't stay and watch you die, but it is going to take days for the pain to kill you, as your magic is drained little by little. Believe me before it is over you will beg people to end it for you. Oh by the way, that prophecy you made up, and the lie about Voldemort's horcruxes, they will never see the light of day now, try to tell them to anyone and your death will become far more pain filled and take so much longer for you to reach the end, you will not be able to manipulate me or anyone else anymore Dumbledore. Goodbye headmaster."
Harry threw Dumbledore's wand on the table in front of the old wizard without a thought. Dumbledore looked down on his wand but there was nothing he could do, the pain in his chest every time he thought of grabbing it was far too severe for him to reach out and lift the wand.
Ten minutes later Harry Potter appeared in front of Harry Potter, Hermione Granger and Ronald Weasley. With a quick wave of his hand the older Harry bound both Ron and the younger Harry, he then turned to Hermione, "Hello my love," he said bowing to the surprised witch.
The older Harry knew from the way that Hermione was looking from him to his younger self and back that he would be able to talk to her without having to bind her. "May I speak?" he asked politely. When Hermione simply nodded her puzzled expression made him smile, and he knew she was waiting for some explanation for what she was witnessing.
"When we are finished here, you and me, I mean the other younger me," Harry said nodding at his petrified younger self, "need to visit the hospital wing and see Poppy. Weasley will be seeing her as well but for totally different reasons. Now I have some thoughts, memories if you will, of things that have happened and would have happened had I not returned. Look into my eyes, see into my thoughts, listen to my memories, I will make them all available to you for as long as I can. But first I have a little some thing I have to do." With that Harry pulled his wand out and freed Ron from the spell that was binding him.
"Hello Weasley, tell me do you still have enough bottle to continue with what was started this summer. Have you spent all that money Dumbledore paid you to get Hermione to the Burrow early this year? Hmm, that reminds me do you still have the engagement ring that Harry gave to Hermione, you know the one you stole and then planned on using it as one you bought giving it to her once she had succumbed to Dumbledore's charms and spells and agreed to marry you," Harry said before calling out a quiet "accio ring,"
Ron looked astonished when his trouser pocket ripped open and the small match box he had put the ring in flew into the older mans hand, still trying to work out who the man was and how he knew about the ring, Ron was far to slow to stop the ring leaving his pocket. Harry turned to Hermione and gave her the match box "You should find your engagement ring in there," he said before turning back to Ron Weasley.
Harry pointed his wand at Ron and sent a bone crushing spell at his left leg. As Ron screamed and fell to the ground and Hermione turned in horror to watch, Harry fired a compulsion charm at Hermione, compelling her to do as he the older Harry had asked and look into his memories when he was ready to share them.
"That one Weasley was for luring Hermione to the Burrow so Dumbledore could place his charms on her," he said as he then sent another spell, breaking Ron's other leg, "that one is for stealing her ring." The next spell that hit Ron broke his right arm, followed by another that dislocated his left elbow, Harry finished with a charm that would give Ron severe pain in his jaw every time he tried to eat more than a normal average person would eat. His last spell took away Weasleys ability to have sex.
"And that my dear 'best mate' is for paying a visit to number four and stunning me as soon as my back was turned, just so that Dumbledore could carry out his stupid plans and you could spend the rest of your life raping my fiancée." Harry said as he placed a silencing charm around the screaming red head. "I'm only sorry I can't find it in me to kill you," Harry said his anger finally showing through the calm features he had been displaying up to that moment.
Hermione turned toward the older Harry intending on yelling at him and if possible disarming him before he could harm the Harry she knew like he had done to Ron, at the same time she was trying to fight the compulsion charm to look into his eyes. The compulsion charm won when the older Harry placed his wand on the floor in front of her, then stood and simply looked at her.
Hermione could not believe what she was seeing, she was sitting at the table in the Burrow with Ron, while Ron admired her engagement ring Molly Weasley had slipped something into her pumpkin juice and as she had become drowsy Dumbledore had entered the kitchen from the living room. She watched as her headmaster first obliviated her and blocked the memories of her agreeing to marry Harry, the beautiful ring he had given her, and the few dates they had been on before the end of term. She then watched as Dumbledore placed three loyalty charms on her, one to ensure she would remain loyal to Ron, one forcing loyalty to the Weasley family, and one to the headmaster him self. She saw Ron pocket the ring, while Molly said it was a good idea that would save him some money, she also wondered briefly who's memories they were but that thought simply vanished as she watched the next set of memories.
Ron was walking into number four privet drive, following Harry up the stairs to his room, as Harry lead the way along the short passageway, Ron pulled out his wand and sent a stunning curse at Harry's back. As soon as Harry fell to the floor Dumbledore arrived and obliviated Harry just as he done to her, he then placed several tracking charms and renewed magical core binding charms on Harry.
There were two more memories after those, the first showing Ron gloating to Ginny over the ring and about how he was going to be the one to get Hermione so he could have first go at her, and the two of them laughing at how funny it would be to have Potter as best man when she married Ron.
The final memory was of the older Harry standing outside the Burrow and hitting the building with a tremendously powerful finite spell. He then stood and watched as the entire house simply collapsed in on itself, trapping Molly Weasley amongst the rubble.
As soon as the final memory was shown to Hermione the older Harry turned to the younger Harry and showed him the same memories. As the memories ended the older Harry started to fade away, a smile on his face telling Hermione that he had accomplished what he had come to do… his final words were to young Harry telling him to keep both him self and Hermione away from the Weasleys and to get to Poppy as quick as they could, telling them she could be trusted.