Ub's idea is a good one...when you join one guild say another guild looks down on you but the remaining guilds remain neutral.
E.g if you join the fighters guild...you get discount at them but the mages guild look down on you..the other guilds remain unchanged.
The Thieves guild can oppose the Assassins guild in the same way....
The rangers guild oppose the necromancy guild???!!
I guess so lets say that necromancy is an evil magical pratice and dsturbs the balance of nature...what with all those resserections and so the rangers get annoyed at the necrs for polluting the forest.
