"The risks of the Joining mean that not all will survive it. Many do not, in fact. Even if that happens, they will still be subjected to a short lifespan and the Calling, in due time. It's not a sacrifice everyone wishes to make, but until we find another way, it's what Thedas needs."

Inessa herself didn't know any of this when she was just a recruit, of course. But even if she had, the young mage would still have gone through with it. Grey Wardens had saved her life in Kinloch Hold, and she meant to repay that.