Oh, it's actually pretty easy.
How to make an AU of a character (Easy)
1. Think of a character that you like. EX. Taki from Friday Night Fever.
2. Think of a strength and a flaw. You can use more than one of each, but make sure not to overdo it. EX. Loves pranks, but is a bit of a hermit.
3. Think of a way to blend the strength(s) and flaw(s) w/ the character.
Here, I made Taki a prankster, but they have a bad habit of going too far w/ the pranks and/or doing too much scary pranks.