Yeah suureee

No, Pen Ward never has confirmed or denied this teory

I dont believe this because a lubglub eats a skull with fionnas hat on it

Fionna isn't Susan Strong, but it's probable that Susan is Finn's mother

I dont know. In one episode there is a creature eating Fiona's hat.

The reason I believe Fionna is Susan is because Gumball may be related to Bubblegum (I know it's Gumbald but close enough), so therefore Gumball is like the generation before Bubblegum, therefore leading Fionna is a generation before Finn. Since she is the only female human, she could have married Martin and had Finn. One day, I think Martin ran off with Finn to exchange for something but lost him in the woods. Fionna went franctic, and fell into where the Hyooman tribes live. She then became Susan, but because of some accident she had to have a transplant...

Anyways, the Lubglub (whatever) that was eating Fionna's hat, may be that her hat fell off and couldn't retrieve it so the tribe gave her the cat hat. The other reason I believe that Susan is Finn's mother is because she sort of remember how to speak English, and when she met Finn she said "sun". Sun sounds like 'son'.