I have some problems with Brother perdiem's badge. How do I get it from him? I have killed the idol and he thanks me for saving him. I can use him for healing but don't get the badge.

Also where can I find Seth's room? One guy says he is on the third floor but I can't find the stairs to the third floor.

Well, I didn't have any trouble talking Brother Perdiem out of his badge. I did once kill him (first time I played the game, before I realized I had to kill the idol first) and he dropped the badge.

Seth's room is indeed on the third floor. It's right next to Marketh's room. However, I've never found Seth in it. I know it's Seth's room only from the hint book and from all the burglar tools in it. Note that I always bluff my way past Seth when he's out front, and never kill Marketh, so maybe that has something to do with it. If you can't find the stairs to the third floor, you might be in the wrong place altogether. The stairs are not hidden. They're at the opposite end of the corridor from where you come up to the second floor from the garden.

Thanks but I already found out about seth's room. This time I went in the room I did found Seth in it. This time I went in Marketh's room first and then Seth's room. I killed Marketh.