Right, so I'm asking you lot as I can't recall something and it's bugging me like hell not to be able to remember. So, here's what I've got:
 

• It's either an novel or a role playing game (like dnd)
• it's set in hell
• Demons are apart of houses
• The houses are in conflict
• The demons drink essence (which has something to do with human souls)
• I think one of the houses is called 'lysander' or something like that
• One of the locations are mountains, or a ring of mountains (I know, generic but I think it's a very prominent location)
• There is magic (again, generic as hell, i know)
• The houses fight over territory including forts (in the mountains)

I think that's all, if I remember anything more I'll add it.
 
P.S. I don't deny that this could be just something I randomly thought up and for some reason I think it's an actual novel/rpg.

http://whitewolf.wikia.com/wiki/Demon:_The_Fallen]Demon: the Fallen?[/url]

i guessed like legacy of kain soul reaver or diablo but prob too obvious

Demon: the Fallen is pretty close, might actually be it.
 
sorry ragnar, it's 100% a novel or table top rpg.
 
Found it!
 
It's Infernum, and the name of the  house I was remembering was 'Lictat' not 'lysander'.
 
Thanks for your help any way!