MacAvoy was a big fish in a small pond - the owner of a club in Dallas. He did well enough to keep the money coming in, hire some toughs to keep his competition in line, and do some deals with organized crime when he could.
So when he met a young woman named Tulip O'Hare, struggling with alcoholism after a bad breakup, he helped her out. He lent her the money to go into rehab and clean up. When she came out, though, he found out that she didn't have the cash to pay him back, nor was she going to pay him with sexual favors. He threatened to put her back in the hospital, but she offered to work off her debt.
The only jobs he had going, though, were hits, and he laughed when she said she could do them. He stopped laughing when she showed him that she was a fantastic shot with a handgun.
He gave her a job - kill a guy who was muscling in on his turf. Easy.
Unfortunately for MacAvoy, Tulip was not the cold-hearted killer that she thought she was. She botched the hit and left town in a hurry.
He got a call a week or so later from Tulip in New York - she wanted to explain and apologize, but he wouldn't have it. He was ready to send someone out to get her, but had no idea where to look.
Imagine MacAvoy's surprise when Tulip came to him, along with her boyfriend, Jesse Custer. They had come with the intention of using Jesse's Voice of God to make MacAvoy forgive Tulip's debt, but they were interrupted by a man from Jesse's terribly past - a hard, true killer named Jody.
Jody walked in, casually killed all of MacAvoy's henchmen, and then sent Tulip and Jesse out to his truck. Before he left, he shot MacAvoy in the head and killed him.