It's the fox, Chapter 21. The quote is short and absolute: 'You become responsible, forever, for what you have tamed.' It teaches that responsibility is the structural integrity of a bond. Without it, the connection is just a passing fancy. The 'forever' part is crucial—it means the responsibility survives moods, distance, and even conflict. It's a foundational promise. I've always thought this quote should be required reading for anyone entering any kind of partnership. It sets the bar high but clear: if you make it unique, you're on the hook for its well-being, indefinitely.