Kristen Stewart's life is like a ''comic book''.

The 25-year-old actress is one of the most famous people in the world thanks to her role as Bella Swan in the 'Twilight' movies and her former relationship with her co-star Robert Pattinson.

From these things Kristen feels as though she has been given an ''assigned personality'' that she has to keep up.

The 'American Ultra' star said: ''It's like I'm involved in a weekly comic book. I have this assigned personality ... which I helped create, I suppose. People stand to make a lot of money on people like me - it's this booming industry, so why would you go and change the character that people are paying for?''

Kristen - who is rumoured to be in a relationship with Alicia Cargile - admits there are things about the fame game she doesn't enjoy but insists she's a tough person.

The Hollywood starlet had to have a strong personality because she grew up with three brothers, Cameron, Dana and Taylor.

She said: ''Growing up with three brothers I wasn't treated better and I wasn't treated worse. I really was one of the boys. I think there's an ambition that's probably innately drilled into me. I like to win s**t.''