Being without it in the pit was one of the worst things. And that is saying a great deal considering they were starved, dehydrated, hunted by monsters, and experimented on. Not that I would have wanted you to experience any of that. Istredd probably would have put up a wall to protect him regardless. It's more about the ability to reach out and touch him.

His fingers trace patterns on Lucifer's back, tucking his nose into Lucifer's neck and staying there contently. Warm and close. Maybe he shouldn't talk about that when they're in a good mood, but it came into his mind.

I've never had a bond this deep. We are trained to be very careful. Most of them have the exact one he just displayed. They can communicate easily but that is mostly it, outside of an important distinction or emotion. He is saying it's deeper than the one he had with Yennefer, although that one was cut off pretty sharply.