It's impossible to protect anyone completely without enslaving them. I think that's something you've never understood because you've always demanded too much of yourself. You blame yourself for your sister's death—
I didn't watch her carefully enough.
What could you have done? Remember her life, not her death. She was brave and happy and arrogant, the way a child should be. You could only protect her more by chaining her to you with fear. She couldn't live that way, not and remain the person you loved.

Chapter 4 (p. 74) - Dreamsnake (1978)