Storm and Fire (Leo Valdez x OC)

Tris has been fighting monsters since she was five. She knew she was different. She knew she was special. She knew she was alone. Or she thought she did. One day, while she was killing some monsters that decided they wanted a tasty snack and bit off a bit more than they could chew, she ran into eight other people who claimed they also fight monsters.
Demigods. 
That's what they call themselves. And, if they were to be believed, Tris was a demigod too.
But who is her father?