Demon invaded his body as a teen while in a haunted forest during a dare. He was able to hold it back thanks to a friend weakening the demon in his soul. He used too much power during a spar with his brother, the demon overtaking his body and killing his brother. He’s been on the run ever since.

Wait, do you play League of legends?! That sounds like it could be yone's backstory... Either way, sounds cool. But what is their class? Race? I think this is cool for a blood hunter, or a warlock. But if it's a light cleric, I would find it not as interesting. For the background, haunted one is an obvious pick. 

So is the demon running around free, is it in control of the body, is it under control or banished back to the nether planes?

A lot depends on this answer. 

Basically either a friend weakened pre campaign or the character overpowered the demon

Def haunted one. I use it for my rogue personally. I actually don’t play LoL

i think its a good back story but is the demon in control 

No. The demon is repressed but at times of extreme emotional pain it can resurface

ok do you think being a bard could make the demon come out

Possibly. It’s meant to be flexible

ok than i think its a really good backstory.

so the character kinda like the hulk

Thanks!

Not really. While Bruce just has to get angry to turn and still has control when the demon takes over, your character is pretty much done for

ok cool thanks for answering my questions. ima out!