James's pov
If James had to choose a moment he deeply regrets, he would choose the moment he gave Harry to Lily's sister.
No, he wouldn't choose to keep Harry, he would just make sure to disinherit him first.
After all, a baby doesn't know he's being disinherited so he wouldn't fight for it in the future.
But, how did his wife said?
'Don't cry about a spilled milk?'
The boy gave him the perfect chance to disinherit him by becoming a Slytherin.
Dumbledore didn't like his plan, said too many things can go wrong. That they need to keep the boy on a leash. James knew that, he also knew that if he won't do it now he might not have a chance later, as the ministry has a lot of rules for disinheriting. So Dumbledore needs to find another way to put the boy on a leash, after all, Marcus has to get his deserving place as the heir of the Potter's lordship.
It was a quiet trip from the headmaster's fireplace to The ministry's wizengamot bureaucracy.
After a few hours of paperwork James pulled out his wand and said: "I, lord James Fleamont Potter, with a sound mind and a strong heart. Without any compromising potions or mind changing spells. With no threats or blackmail. Take my son Harry James Potter's right is an heir to the Potter's lordship. Knowing that by doing so, he is no longer my son. Knowing that he would get 100 Galleon for every year he's left until he is 17 and full payment for his studies from the main vault. I give the heirship to my son Marcus Evens Potter, with the knowledge that once I died he would inherit me. So Mote it be. Lumus" a strong light washed over the room, and James smiled.
Harry's pov
Harry really wanted to finish all of this quickly, he's finally not a potter so no he just need to choose a different family name.
He had quite a few options:
1) Wilkerson, as a memory for his parents.
2) Malcolm, as he was called by that name for 7 years.
3) Peverell, as an old name which would also symbolize his past life and death.
In the end he chose Peverell for a couple of reasons, but non were more important than the fact that it would drive the Potters and Dumbledore insane. The Potters cause it would be like saying that instead him being disinherited, he just had didn't want to be with the Potter last name and Dumbledore because he would wander what does he know about the deathly hollows.
"I take off my name Harry James Potter, and take on the name Harry DJ Peverell, I take my middle and last name off knowingly that by taking them off I could never take them on.
So Mote it be. Lumus"
After that James went back home and Harry went to Gringotts