Tenacity is a cynical, cruel and disillusioned bounty hunter. A frequenter of the shanty towns in various cities, his reputation as a ruthless tracker precedes him. He is often seen with his dog, a terrifying mastiff as cruel as he is. Roy is no stranger to Tenacity, who sometimes worked with him in the slums of Aurora where Roy lived before the war against Abundance.
After speaking to General Honour Grant you go to rest at Abandoned Building. He will be waiting up the ladder with 2 dogs. You fight them separately. If you took Mary with to see General Grant, she will get back up if KO'd by the dogs. With the small space he should be the easier to finish since he only needs to be beaten halfway to turncoat again.
He has Charity locked in the bedroom. So after the conversation where you can have him as a companion or kill him, you have to free her then go to her bar to finish the quest and get 8000exp.
He fights with a gun and melee much like Innocence but slightly tougher.