It may be a long shot, but I have an idea in mind that I am just dying to turn into a long term line and would love to find someone to make it a reality with me.
Single (or married...whatever you want his status to be is up to you) father sends his only child off to college. She is still in state, but gets so busy that she only travels home during vacations and holidays. During one such break, she brings home a friend (that would be my girl) who's own family is away and wasn't looking to be alone. Things are fine, very casual, with the two girls spending time shopping and hanging out with his daughter's old friends, whatever. One night, the friend decides to hang back while the daughter goes to spend the night with one of her other friends, leaving my girl and the father alone in the house. Now how the two of them end up in bed together is up for discussion, but I'm thinking it's something along the lines of he can't sleep, goes down stairs to get a drink and catches the friend playing with herself in the spare bedroom.
I would like for this to be long term, so I'm thinking that perhaps every weekend, the friend travels back to spend time with the father, simply telling her friend that she is seeing someone at a different school and leaving it at that. All these little details can be sorted out, though, so if you want a custom or feel like making one, just let me know. I'm open to who can be used as the father's face, though so guys I had in mind are Jonny Lee Miller, Gerard Butler and Jeffrey Dean Morgan. I am looking to do things strictly through journals, but I'm thinking since the "relationship" would be long distance, customs can be used as well as actually scening since they would keep in touch through texting (very, very, very dirty texting, of course). Other ideas are welcome, but I tend to like things that are very smutty (but with plot, of course). I can give you a list of kinks I like and my hard no's if necessary, though I try to keep a very open mind and am always willing to try new things.