If you give a fangirl a character, she's going to ask for a cute butt.
When you give her the cute butt, she'll probably ask you for an awesome outfit.
When she's sated, she'll ask you for an awesome best friend.
Then she'll want to inspect their relationship to see if it's a ship or not.
When she decides it's not a ship, she'll ask for a super cute tsundere companion.
Then, she'll ask for a romantic relationship with the cute tsundere companion.
She'll start shipping them. She may get carried away and write fanfiction. She may even start drawing fanart as well!
When she's done, she'll probably create a thousand headcanons. You'll have to sate her with only a couple of them. She'll horde them and create a den of headcanons, and then ask for a tragic past.
When she sees the tragic past, she'll get so excited and want to write even more fanfiction and draw even more fanart.
When she sees her fanfiction and fanart, she'll get excited and post it on Tumblr.
Being on Tumblr will remind her of canon.
Reminding her of canon will make her ask for more cute butt. And chances are if she asks for more cute butt, she's going to want a character to go with it.