The Punisher and The Assassin

Alex McKinley, sometimes known as Olivia Anderson (it's complicated) is an ex-SHIELD officer. Instead of retiring her skills, she put them to use and became an assassin. She runs into Frank Castle on a mission one evening. When she returns to New York, she searches for Frank, who's supposedly dead. She helps him finally finish the mission he started. They find that they're much more similar than they're willing to admit. The realization leads to much more violence, cursing and a complicated friendship (if that's what you want to call it).

*I don't own Marvel's Punisher.