Before the events of Tales from the Borderlands, Felix was a lone con artist but one day, Fiona and Sasha made an attempt to take his wallet, Felix caught them in the act but instead of punishing the girls he took them in as his children and raised them into a life of crime.
Due to years of experience, Felix is able to hack into any sytem without fail, even codes from the Hyperion Corporation, he is also able to make a perfect replica of a Vault Key and many other high priced artifacts that's worth a hight price and sell it the rich.
Felix does not trust anyone, he believes that any is capable of being a traitor, Felix wanted Fiona and Sasha to grow up on this ideal so they can be strong and survive in the harsh and deadly world of pandora, Not trusting anyone was Felix's final lesson to the girls, Felix stole the ten million dollers for himself and he left Sasha, Fiona, Rhys, And Vaughn to be killed by the bandits, but unfortunately for Felix, Vaughn put a bomb on the case of money and it would blow up if the correct code was not punch in, unaware of the bomb Felix opened up the case and he blew himself up, body parts of himself and parts of the ten millon dollers went playing all over the bandit camp.
Alternatively, Fiona can warn Felix of the bomb, causing him to throwing in the air before it explodes. Thus, saving his life.
If spared, he'll reappear in the finale.