Who is Law Kincaid from Long Time Coming and what is their importance?

Law Kincaid arrives at Marnie's house making accusations that she's been writing him letters saying that he has a son. From the moment she recognizes him, Marnie is forced to deal with memories of her own childhood love for this man. Law doesn't recognize Marnie until she begins to explain about Sharon. He's been living the life of a successful bachelor.

On the day Law meets David for the first time, he has a date with a woman named Suzette. He has given the woman the key to his house and his alarm code, but has forgotten, and he admits that he doesn't remember their earlier meeting.

It's interesting that once David begins staying with Law, Marnie discovers that Law has many of the same rules for David. He stops having parties because he has a teenager in the house. Marnie thinks that Law's interest in David is merely a passing phase, and that he won't want to deal with the long-term impact of having a teenage boy in the house. Law, on the other hand, quickly finds himself falling in love with Marnie and wants to marry her.