There's always a catch. When a Witcher asks for "what you find at home yet don't expect" in return for saving someone's life, neither party really knows what form that reward will take. It being an unknown quantity, one can usually be safe in assuming it will be somewhat meaningful. There's always a catch, after all. I like ambiguities like this, and The Witcher 3 is full of them. You've got your more standard video game ones, like not truly understanding the wider consequences of your actions, or never having a complete grasp of your companions' intentions. But it's home to many more, ones that are much more specifically, well, Witchery.
