The difference a name makes
Disclaimer: JK Rowling owns the rights to the Harry Potter world. I am just having fun.
Harry Potter was upset, here he was this close to be free of the Dursleys and then to have it not only yanked away, but now fighting to save his godfather from being killed, and then letting him go on the run from the law again. He turned to Hermione, who was sitting next to him, as they waited with Buckbeak for the time when they could be sure that Sirius would be alone in the tower, and available for them to rescue him.
Hermione had already told him that they could not change what had already happened, so he started thinking about changing the future. His first thought was to get Sirius to look like someone else, thus allowing to move freely without being arrested by wizards or muggles. After some thought, he remembered a movie he had seen, he asked Hermione what she knew about plastic surgery. When she looked at him as if he had gone off his rocker, he explained what he had been thinking of to her. She thought about it, added some suggestions, and told him it could work. They decided to involve Professor Lupin, once he reverted to human form, in their plans, as he could move around freely. Hermione would also speak with her parents to get at least information, if not direct help.
When they eventually rescued Sirius, they told him quickly to contact one of them, or Professor Lupin, as soon as school closed, and not to get too far from London, as they had some ideas as to how to get him freedom.
The next day when Harry went to speak to Professor Lupin, he saw him packing to leave the school. Lupin explained to him that he had been outed by Professor Snape, and was leaving before he was forced to by Dumbledore. Harry explained quickly to him his plans to get freedom for Sirius, without going through the court system. Lupin looked at him and laughed, he told Harry that it was a plan worthy of the Marauders at their prime. Lupin made some small changes to the plan, as he would be free to help Sirius to a greater extent, without the underage magic restriction that Harry and Hermione faced. His most important change was getting a letter of introduction from Hermione to her parents, asking them to help Lupin in his quest for a plastic surgeon. He also told Harry that he believed that Sirius should have access to funds, thus there was no need for Harry to use his funds. Harry asked only that Sirius come to spend time with him by the Dursleys, once he was not otherwise committed. He regretted that he could not invite Professor Lupin, but while Sirius could stay in his bedroom as a dog, Lupin could not. He could however come with a doggy Sirius and ask Harry to look after his dog for him.
When school ended, Lupin was there to pass a note to Harry on the wizarding side of Kings Cross station. The note simply asked him to advise his guardians that an adult wizard would be coming to see Harry the next day.
Lupin and his pet dog turned up the next day. The Dursleys were not happy, but had no time to raise objections as Harry had " forgotten" to give them the note until that morning. Lupin took him to the nearby park and they discussed the progress of the plan. Sirius had gotten access to his vault, so money was no longer a critical issue. They had purchased a dose of polyjuice, and used a random muggle's hair to get Sirius, in disguise, into Ollivander's so that he could purchase a wand. They had used a muggle who looked slightly like Sirius, and had taken pictures of the changed Sirius. They had spoken with Hermione's parents and had gotten the names of plastic surgeon's in the Dominican Republic, an island in the Caribbean. They were wary of using a UK, US or European doctor, in case they recognised Sirius from the wanted ads, so they had gotten information on surgeons in other countries. They had an appointment to see the surgeon in the DR in a week's time, and if he was willing to perform the surgery, he would do it two weeks later, with a recovery time of one month. During this period, they would set up a false identity for Sirius in the USA, as a distant relative of Sirius, called Samson Black. They would also arrange a will for Sirius to leave his estate to this relative, with a request for him to take over the guardianship of Harry Potter. Harry was happy, his plan was succeeding. Lupin also asked Harry if he wanted to come with them to the DR and stay with them while Sirius was recovering, Harry was happy to agree, time away from the Dursleys, time with Lupin and Sirius, time on a Caribbean island, hell yes!
Everything worked as planned, Sirius and Remus left for the DR a few days later, three days after that Remus returned and took Harry back with him, as the operation was going to go ahead. While Sirius was recovering, Harry spent a combination of time with him and Remus, talking about what had happened to him in his first two school years, they already knew about his third year. Sirius was especially concerned that Voldemort, or Tommy boy as he called him after he heard about the events in the Chamber of Secrets, was still alive, and that Peter was prophesized to bring him back, more terrible than before.
Sirius became even more concerned when Harry had a nightmare about Peter, Tommy boy and a stranger, where they were planning to use Harry in some way which apparently would be detrimental to Harry. They immediately started reviewing their plans. From Harry's memory of the incident, something was going to happen at Hogwarts and Harry was going to be involved in it. The first question was thus going to be, what was going to happen at Hogwarts. Remus promptly made a return trip to England on his own, and after a meeting with Percy Weasley, he made a stop at the Ministry to check their library archives, and then returned to the DR.
On his return, he told them his findings, The TriWizard tournament would be held at Hogwarts this year, to be entered in the tournament, your name had to be selected by an object called the Goblet of Fire. To enter a name only required throwing in a piece of paper with a person's name into it. Once selected, the person named must compete, or they would lose their magic. Harry and Sirius were astounded that Dumbledore, after being aware of Tommy boy's presence, was going to hold a dangerous tournament! Definitely they needed to plan. With knowledge of what they were going to face, they talked about it for the next few hours.
They came up with a two part plan. The first part was to avoid getting Harry entered in the tournament, the send part was to keep Harry from being captured/used by Tommy boy.
The solution to the first part was easy, it was the second part that was problematic. The simple solution that they arrived at was a variation of what they were already using for Sirius, change Harry's name just before the Goblet started to accept entries. If no one realized that his name was changed, his current name would not come out of the Goblet. He could not be bound to a contract in another name. Sirius looked at Harry and Remus arguing about the resolution of the second problem and suddenly burst out laughing. He told them, don't worry, he had come up with a solution. He told them that once Samson Black was listed as Harry's guardian, Samson could pull Harry from the school. Eventually Harry agreed. The last problem was someone, here Samson coughed Dumbledore or Snape, performing legilmency on him and finding out his plan. They started teaching him oclumency, but the short term solution was getting him some prescription shades, which were charmed to allow him to see even in poorly lit areas, but would block anyone seeing his eyes.
By Harry's birthday most of their plans were sorted out, and they enjoyed the day by going to the beach, as Sirius had finally had his bandages removed. He had done his animagus transformation, and they were happy to see that he changed back with his new face. Since the operation on his face was not magical, it would not fail under magical tests. They had also arranged to change his name legally to Samson Black, so that even under veritaserum he could swear that he was Samson Black.
They had plucked some of Samson's hairs before he had the operation, and they used polyjuice on a dying vagrant to get a corpse that would be used to " prove" the death of Sirius Black. They had already checked with the Goblins, and since Sirius had no convictions against him, his will would be executed, allowing Samson Black to inherit his estate and obligations, including guardianship of Harry.
In the last week in August they returned to England, collected Harry's booklist and went shopping, they contacted the Graingers and Weasleys and warned them of the potential danger, without letting them know of their plans for Harry. They skipped the World Cup, as they were busy filing documents at the Ministry, thus only heard later of the Death Eater activities after the match.
Sirius got even more worried and got a portkey for Harry, which he was to use if he was in trouble. They also reminded him to use the map to check on who was near to him.
By the second day of the new term, they had identified the plant as Barty Crouch. After visiting the Ministry and finding that Barty Crouch was also there, at the same time that he was in Hogwarts, they were puzzled, why was he in Hogwarts disguised as Moody, why was Moody hiding in his office, and why was someone impersonating him at the Ministry. They decided to wait and see. They however decided to adjust their plan, by not revealing the name change immediately, if it came out of the Goblet. They however decided to go to the Head of the DMLE, Amelia Bones with their concerns about a plant at Hogwarts and/or the Ministry.
The night that the other schools arrived they were even more puzzled, as Harry contacted them by mirror to state that there were two Barty Crouchs' at Hogwarts that night. They told Amelia and she decided to make a surprise appearance at Hogwarts the next night,when the Champions would be selected.
The next evening, Amelia floo called Dumledore and asked to come thru with four Aurors. She then told him they had concerns about some of the people at Hogwarts, and asked him to tell no-one of their presence.
The dinner proceeded and the goblet started to select the Champions. As Harry suspected, after Champions were selected for the three schools, the Goblet lit again and the name Harry Potter came out. Harry smiled to himself, and promptly got up and swore an oath that he had not put his name in the Goblet and therefore could not understand how the name Harry Potter came out of the Goblet. Dumbledore and the Ministry Crouch insisted however that he must go to the briefing room. Harry then pointed out that it was a TriWizard contest and three magicals, from the three schools were already selected. A fourth selection was thus an aberration and should cause the whole selection process to be thrown out. Crouch insisted that Harry's name came out of the Goblet, thus he must participate or lose his magic. Harry laughed at him and told him that the Ministry were fools if they used an object which could make a contract with someone where someone else could put their name in it. Eventually after dragging it out enough that everyone would realise that he was doing it under protest, he walked into the briefing room, the three Champions had already been removed, and as soon as the two Crouches entered the room, they were stunned. The other persons were told to give unbreakable oaths that they would not communicate with anyone about the events that happened after they entered the room, until released from the oath by the Head of the DMLE. The Crouches were then taken to another room and the TriWizard discussion allowed to continue in the first room.
In the second room, the Crouches were searched and their wands taken from them. Within a few minutes, " Moody" had changed back to someone they believed to be dead, Barty Crouch junior. They stunned them both again, whilst they worked on a strategy. Eventually they decided to stun and disillusion Crouch Senior, while they questioned Crouch junior, then they would stun and disillusion junior and question senior. This way, neither would be aware that the other had been questioned.
The questioning revealed that Crouch Senior had broken junior out of jail and had hidden him away, controlling him with the Imperius curse. Junior had however recently overcome the curse, and had put Senior under the curse, while rejoining Voldemort who was in hiding at Little Hangleton. Remus, who had asked to be present at the interrogation, asked Amelia to keep the arrests quiet until after the first task had been completed. He told her they had something planned for Voldemort, and wanted him to continue to believe that his plan working, rather than his escaping and developing a new plan. After some thought, she agreed.
The Daily Prophet the next day was full of the news that Harry Potter's name had come out the Goblet, no mention was made of the missing Crouches.
Hermione was concerned, for as time passed, Harry was not concerned about the task, all he would do was smile and tell her that he had everything under control. Eventually, the day of the first task approached, and still Harry had done nothing to prepare. When Mcgonogall came to advise him that the Champions were to go the venue now, he reminded her that he was not a champion, and he would accompany the rest of the school. She responded that as a Champion, he could not be allowed to see the the event before his turn was called. He then told her that he would stay in the Great Hall, if she wanted to, she could keep him company to ensure that he did not sneak down. He then whispered to Hermione that all would be explained soon.
The morning passed, and it was announced that as the fourth Champion had not gone to the tent to choose a position, he was given the fourth position.
When all the other entrants had completed their task, Harry went down to the tournament area and asked to speak to the judges. His first statement was to ask them to swear on their life and magic that since Harry Potter's name came out of the Goblet, then he must compete or lose his magic. The judges were unwilling to do so. Harry then pointed out that he had not put his name in the Goblet and was being asked by them to risk his life or lose his magic, yet they were unwilling to do the same as confirmation to him and the schools in the audience that Harry Potter had to compete.
By this point the students started to realise that Harry had a point, why were they forcing Harry to participate when they were apparently not certain that he had to.
Harry then turned to the audience and told them that because of the risk to his life in previous years, he had been concerned when he heard that the TriWizard competition was restarting. He had spoken to the Headmaster, and had not only received no assistance, he was being forced to participate in a competition which had resulted in the death of champions, whilst he was below the official age of the competition. If the school was that dangerous to him, he was therefore resigning from the school and would attend a school in another country.
Dumbledore immediately responded that as an underage student, only his guardian could withdraw him from school or change his school, and as he, Dumbledore was his guardian, he was not allowing the withdrawal.
Harry then told the crowd that he now understood Dumbledore's insistence that he be in the competition, it was not just the name coming out Goblet, but since Dumbledore thought he was his guardian, Dumbledore believed that he could approve his entry as his guardian, regardless of Harry's wishes. He added, whilst everyone was looking at Dumbledore in shock, that thankfully, Dumbledore was not his guardian, therefore he could not stop his withdrawal. He told Dumbledore that since Sirius Black was the guardian appointed by his parents, and Sirius had no legal convictions against him, upon Sirius's death, Sirius's will was executed and his will appointed one Samson Black, an American relative of Sirius as his guardian. He then handed over copies of the relevant documents to Dumbledore, telling him that the originals are with the Ministry and the Goblins.
Dumbledore was in shock, but recovered to point out that he was going to lose his magic as he did not participate. Harry looked at him and laughed, No I will not, was his response, as he started to walk away, he stopped looked at the judges and told them, that since he was worried about the danger of the Goblet being used to enter his name he had simply changed his name before the Goblet was lit, without letting the school know. Contracts created after that time must use his new name, since his old name came out of the Goblet, no contract was created with him.
Harry then hopped on his broom and flew away from the school.
Two days later the headlines in the Daily Prophet were all about the deaths of a number of individuals, the only thing these individuals had in common was the fact that most had been accused of being Death Eaters.
Samson read the newspaper in shock, then burst out laughing, Harry and Remus looked at him in shock. He responded to their unasked query by saying that since they had expected the name Harry Potter to come out of the Goblet, and non participation would cause a loss of the entrant's magic, he had changed Voldemort's name from Tom Marvolo Riddle to Harry James Potter. With the loss of his magic, apparently all the Death Eaters perished, which was an unforeseen, but not unwelcome side effect.
AN
None of the "good guys" in the books were proactive they were only reactive.
Harry did nothing to save himself when he knew he was in danger before the fourth year began, even when taken to the graveyard, his response was wait and see, not run for your life.
Dumbledore did nothing to help him, a simple emergency portkey could have helped him and Cedric in the graveyard.
You have this powerful object, and no one thought of using it to stop Voldemort.
The solution above required no extraordinary feats of magic, or wealth,or even knowledge of the prophecy.
Only the death of the Death Eaters was AU
Since all "versions" of Riddle would have lost their magic, the Horcruxes would also have lost their magic also.
No pureblood would have expected plastic surgery, thus their magical tests would have failed.
Another idea is having Sirius be a metamorphagus.
What was Harry's new name? It was not critical to the plot, I was thinking about Englebert Humperdinck, but instead settled on Harry Houdini.