Who is Jason Osteen from The Husband and what is their importance?

Jason Osteen is the dog walker and Mitch's former roommate. The two lived together for two years before Mitch learned that Jason was involved in illegal activities and moved out of the apartment, breaking off all contact with him. Mitch later learns that Jason is one of the men tAnson hired to work an illegal case with him, and that he was a part of the group Anson cheated when he did not give them their fair cut of the payment. Jason agrees to walk the dog, believing that his fellow kidnappers are going to shoot the dog. However, the kidnappers shoot Jason in order to raise the amount of money each man will get.