How about a former [url=http://dragonage.wikia.com/wiki/Seekers_of_Truth]Seeker[/url]? Doesn't have to be another "magic genocide" faction; instead it could be more focused on corruption within the Chantry, Templars, etc. Sure, they and the Templars share roles regarding the investigation of mages, but it has a lot of other duties to choose from.