Performing a prank can be a very tedious job, requiring research, planning and perfect execution, for which the Marauders had been famous. Remus spent a few days on research, mainly looking for Harry. He checked each and every orphanage he could find in the British isles. He used all his contacts to find if any magical family had recently got an additional child. He even tried talking with Dumbledore, although he didn't think he'd get a straight answer.
"I've been his uncle in all but blood. The child knows me and likes to play with me. I really feel I should visit him, now that he's been deprived of his parents. It is my duty in more than one way."
The old man insisted. "He is much safer if nobody knows his whereabouts and nobody visits him. I made sure he is well kept and protected by the strongest wards Magic can give. He's too important to compromise his security, and you're a known friend of his parents. Being seen near his new home is a risk we can't take."
"Who do you want him protected from?"
Dumbledore sighed, as if he had already explained it many times over. "We've not captured all of Voldemort supporters, you know, and too many of those captured used the 'imperius' excuse to get free. They may want to finish the job begun by their master and kill the boy. We can't allow it."
Remus was still unconvinced. "I wish Harry long and Happy life, but why do you keep insisting he's so important? He's just a toddler, barely more than a baby."
Remus didn't expect a straight answer anyway, yet this conversation gave him enough of a clue to search some more. Unlike most purebloods, the muggle world was not strange to him. Lily had a lot to do with this, as well as his affliction, which forced him to find jobs wherever he could. He knew roughly where Lily's sister lived and a quick search in the phone book gave him the exact address. Using a disillusion charm, he visited the place and could distinctly hear the two toddlers in the house. That was all he needed to know.
He could now join his friend to continue planning.
The long, elegant limousine advanced slowly into Privet Drive, attracting a lot of attention. It stopped in front of number 4. The chauffeur, who was wearing a finely decorated uniform, went out and opened the passenger door for the aristocratic looking young man who stepped out, looked around for a few seconds and proceeded to the door of the house, where he knocked politely.
Vernon Dursley opened the door and was a bit overwhelmed when he saw the car and the man in front of him. They both looked more classy than he had ever seen. Trying to be on his best behaviour he asked, "May I help you, sir?"
"Mr. Dursley, I'd like to talk with you, if you don't mind."
Vernon nodded dumbly and continued staring at the stranger, who was wearing a tailored overcoat with fur trimmings, appropriate for the weather, and a quality hat which covered his black hair. The man's eyes seemed familiar, yet he didn't remember anybody with a trimmed black beard.
"Inside," the man reminded Vernon.
"Of course, sir. Do come in," Vernon said in his politest tone, moving aside and letting the man in.
Petunia, who was waiting inside, proved to be more observant than her husband. "James? It can't be! They said you were dead!"
James smiled reluctantly as he removed his hat, revealing his untameable black hair. He bowed exaggeratedly before saying, "Well, Tuney, the rumours of my death were premature, as you can see."
Petunia was not impressed by his smile. "Where's Lily?" she asked pointedly.
James turned serious at once. "Alas, she's been murdered. I couldn't save her. I'm sorry."
"Then why are you here?" she shot at him, "And why now?"
"I believe you may know where Harry is," James said.
"Why should we know where your freak of a son is?" Vernon spat. Now that he also recognized the man, he lost his respect and his inhibitions.
Vernon didn't notice any movement, but James was suddenly holding a wand, pointing it at his face. Vernon froze as James moved the wand in controlled movements, saying some words he didn't understand.
"Somebody put a compulsion curse on you, Vernon, and maybe on Tuney as well. Please sit down on the couch and let me rid you of it."
The Dursleys did as requested, although Vernon was grumbling.
James muttered a spell to make them fall asleep. He then used his auror training to check both muggles for any spells. He found some compulsion charms as well as tracking charms. He removed the compulsion and moved the tracking charms from the persons to the couch. Whoever had cast them would not know they were neutralized. He then went into the backyard and waved his wand, chanting some other spells. His frown deepened at what he found there. A few minutes later he returned inside and awakened Vernon and Petunia.
"Please, James, tell me what happened at Halloween," Petunia pleaded, her eyes tearing up, as Vernon was trying his best to comfort her.
James told her all he knew.
"Then who did they bury in your place?" Petunia asked, once he finished his tale.
"My doppelgänger was also built like me, having bones, muscles and blood created by magic. The killing curse had probably blasted it to pieces, and yet it looked similar enough to me for others to make that mistake. Now, after checking you over, it seems to be even more justified than before."
"What do you mean?"
"I've found that you both were under a compulsion curse, which I removed, and there was also some kind of compulsion cast on the house, which I also removed. Now, what do you know about Harry?"
Petunia's face contorted in horror. "Oh, dear! I've been treating him miserably. He's here, sleeping under the stairs, the little darling."
She hurriedly walked to the cupboard under the stairs and took out the sleeping baby, cradling him tenderly. "I don't know why I treated him this way. I'll never be able to forgive myself for this!" There were new tears in her eyes.
"It was those compulsion charms that made you act this way. I know you would have never treated Lily's son worse than your own," James tried to comfort her, while Vernon looked as if he wasn't believing his own eyes.
A sharp cry from the upper floor made Vernon stir. "I'll bring Dudley down," Vernon volunteered, seeming quite eager to do something, or to just get away from the uncomfortable conversation.
By the time Vernon returned with Dudley, Harry was already awake as well, sitting on his father's lap. Petunia was telling James about finding Harry at her door and about the accompanying letter.
"A few days later, Severus Snape brought us a package with stuff collected from Godric Hollow, things that were obviously magical," she added.
"You know Snape?" James wondered.
"Unfortunately yes. He used to live nearby, at Spinners End, which was the low-class area near our neighbourhood. He became friends with Lily when she was about eight or nine and he was the first to tell her she was a witch."
"But why would he bring anything here? I'm sure he was a Death Eater... a follower of the Dark Lord."
"I don't know. I've never liked him. He only gave me the box and told me that Dumbledore asked him to deliver it. He looked like he disliked the mere idea of talking with me."
As much as he would have liked to discuss is some more, he knew that Petunia was unable to give him any more information.
James didn't stay long after that. He helped Vernon move whatever was in the spare room to other rooms and helped Petunia set the spare room for Harry.
"I'll come tomorrow evening to discuss how to proceed, if you don't mind," he said, once the room was ready.
"You know you're always welcome," Petunia reassured him. Vernon also nodded. Although he feared Magic, he couldn't help liking James.
Moony was waiting for him at the muggle hotel, where James was checked in as Mr. Jacques DePoitiers. It wasn't even a lie. The Potter ancestors had come from France, where another branch of the family still existed. The English didn't like the French name, making it into "Potter". They then married into the Peverell and Gryffindor lines, finally becoming the only known descendants of those lines.
"How did it go?"
"Better than expected. They were both under compulsion charms and there was also some kind of compulsion ward on the house. Once I removed these, they returned to be the civilized people I've known before. I also tackled the tracing charms cast on them. I've left the protection wards, though."
"Why did you leave Harry there?"
"Without the compulsion charms, they're going to treat Harry nicely, feeling guilty for how they were acting for the last few weeks. I believe the old man has a spy nearby – a house there was bought two days after Halloween. I think we may need to put some other child there."
Moony smiled with evident mischief. "That's a prank worthy of the Marauders."
He turned serious again. "What shall we do about Padfoot?"
"I've contacted his cousin, Andromeda Tonks. She's a lawyer and she's going to force the ministry to put him on trial, where he will surely be found innocent. I'm paying all the expenses, and I'm quite sure Sirius will insist on returning every knut back, once he regains his freedom."
"That's a sure bet," Moony agreed.
It took a few more weeks to finish everything. Sirius Black was interrogated under Veritaserum and proved innocent of all charges. He was released immediately and compensated nicely for the few weeks he had spent in prison. Andromeda also made sure that his innocence was made very public, to remove any doubts some might have had.
Despite his short stay in Azkaban he would need quite some time to recuperate and James... sorry, Monsieur Jacques DePoitiers, invited him to do it at his villa on the French Riviera, although it was out of season.
Once the trial was over, James also needed to finish the arrangements with the Dursleys.
"You know, I hoped to have at least two children, but after Dudley's birth, the doctors told me I shouldn't risk another pregnancy. I barely managed to stay alive, you know. When I got Harry it made me think again, especially after you removed those nasty spells..." Petunia told him.
"I know you love Harry, being all that remained of your sister, but he needs to grow among people who do magic, not ones who fear it."
"I know, James. It's just..." There were unshed tears in her eyes.
"Why won't you adopt, then?" James suggested.
"We tried, about three weeks before Halloween. It's a lengthy procedure and there's a long queue. There's not much chance we can get approval, especially as we already have a child of our own. It seems that childless couples have better chances."
James smiled. "I believe I can help you and that would also fool the old man and his spies."
The Dursley were just too glad to accept his help.
Although not quite legitimate, some well placed money proved very efficient in speeding up procedures and overcoming bureaucratic obstacles. Some discreetly placed spells proved to be even more so.
A few days later, Harry Potter left Privet Drive with his father, while the Dursleys welcomed another one-year old boy, one with dark hair, blue-green eyes and an accident scar on his forehead. They decided to call him Henry.
Mr. DePoitiers left Britain the same way he came in, using a muggle flight. He was accompanied by his son and his two trusted friends. Nobody in magical Britain was even aware of their departure.