Weylon

Weylon is the loyal servant of Brother Genitivi. When you meet him he seems rather nervous and withdrawn, continuing the conversation reveals why.

Involvement
Weylon greets you as you enter Genitivi's house at Denerim, when you try to enter the locked door in the top of the house he asks you not to, trying again will result in him attacking you and your party. However you try to get Weylon to spill the beans, either through cunning, annoying him or entering the door, he will turn hostile.

If you enter the room after you have defeated Weylon you will see the reason, the one who attacked was an imposer, the real one is lying down by the dresser under a sheet.

Strategy
Simply mass Weylon and use appropiate skills until defeated