All this is from memory, so some stuff is likely incorrect:
I read a first volume of a trilogy, now more than 20 years ago. On the back it was praised as the Tolkien who didn't need vast landscapes.
The story is about a castle and a noble family, where somehow an outsider, a real outcast, gets the opportunity to squeeze himself in. The father is some sort of king; the whole story all takes place in his castle. The first book ends with a separate building, the library, being burned down to ashes. It could be this was needed to cover up a murder.
It is hard to give details, as I somehow mostly remember the weird atmosphere, with a main character that is definitely not 100% likeable. He is continuously planning, treating the whole family as pawns in a strategy game to ensure he can stay in the castle and enlarge his importance.
Does anybody have the faintest idea who the writer would be and what the title of that trilogy would be? (If so, I'd be impressed and verrry grateful.)