Harry Becomes an animagus
After Harry Finds out his dad was an Animagus, He starts to secretly Study how to become one.
He asks Sirius For help, So Sirius sends him Notebooks that he and James had made documenting How they became animagus.
He also sends His, James and Remus Marauders notebooks, That had all the spells and potions they modified to Prank people. And All the pranks they did how to do them and how they made and Charmed the map.
And all the other books the black family had on animagus.
Harry gets very emotional reading his father's journal, Seeing his father's handwriting for the first time and it also had things about his mother that his dad had wrote down, And He loves reading the
Marauders Notebooks About their pranks.
His father, Sirius and Remus were geniuses For Altering useless spells to make excellent pranks. So Harry gets the idea to alter harmless spells to become more deadly.
Harry with the help of the Notebooks Becomes an animagus in a couple of months.
He is an wolf Animagus (You can choose different if you want)