In 2006 I read a rather new fantasy novel, so probably written in 2003-2006. Might have been part of a series or trilogy, female author I think.
The protagonists were a team of friends/ associates who caught on to a conspiracy to take over the world. The protagonists were a woman, a (ex)legionary (they start an affair) and two brothers who are mercenaries. The conspirators were a inhabitants (exiles?) who lived on a very barren island. They wanted tot take over the world to make a living in a more inhabitable place. They used an unknown form of magic, invading the minds of their victims.
I do remember one fight-scene vividly. One of the protagonists, a rather dim fighter is hypnotized/ possessed by the main villain. The villain tries to take over his mind, by confronting the fighter with his worst memories of bloody fights. To which the fighter responds by completely accepting his own brutal nature and brutal deeds. The fighter is rather surprised that the main villain, who did more or less the same brutal things, is very traumatized by them. His last question, before instinctively crushing the mind of the villain is: but why did you do it all, if you did not enjoy them?
I hope you can help.