well as the topic says I'm looking for certain stories/plots that I haven't come across jet (or maybe just think I haven't read jet because I have a bad memory XD)

well the first big category is age gap:

1. The story is told in the view of the older guy... I haven't come across a yaoi were for example the story about a high school boy/student and salesman/businessman is told from the view of the older and working one... maybe some extras or so but never the bigger part of the story

next would be a bit of fantasy.. but it doesn't have to be yaoi since I don't believe that there is a story like this:

2. A demon getting summoned from a human to the human world ...sound like something that happened a lot?.. well but probably not told from the view of the demon... as in the story starts in the demon world and the demon suddenly gets summoned and has to get used to the human world... or something like this >.<...

....thats it for the moment since I forgott the last one...yes, my memory is bad...

hope somebody can help me out with this ^^

Kuma to Interi was a really good collection of one-shots (well, I haven't really read much yaoi to be honest), but I liked them. If I remember, the second should fit your first request for an age-gap... But read all of them.