Where was the character Born?
Who are/were the characters parents?
Why did they leave home to become an adventurer?
What did they leave behind?
What are their goals?
What is something the character fears? Like dying alone for example.
Also really think about and describe what the character looks like, and how they act.
What's their world view? Are we all doomed or is there hope?
How trusting are they?
There's some really good videos on You Tube for character generator guides.