Mezcaal is an anthropomorphic coyote who is a bartender and the wife of Raphael in the future. She and Raph both work at a bar which appeared to be named Turtle's Island. It appears she's a tough character and doesn't put up with anyone's attitude. As she once kicked out two customers after they ignored her warning not to fight in her bar.
Its not truly known if Mezcaal knows about Raph's ex, Ninjara. As it appeared in issue 61, Future Raph seemed melancholy seeing his past self with her and apparently wished he had Ninjara (preferable older) by his side. This could mean that was alternate future Raph or this was before he met Mezcaal.
Since Mezcaal is Raph's wife in the future, this makes Raphael the first turtle to be married in a licensed TMNT story. Other turtles in various incarnations have had love interests, but none were married to them until Mezcaal. In the Mirage TMNT story "Swan Song", Leonardo and Radical became each other's lover and soulmate, though it is never revealed whether they formally married.