This was Istredd's insistence and he said it because he knew he would be reluctant once they had to do it, so it was just thinking ahead. He just shoots Lucifer A Look and takes his journal where his lesson plans and gestures toward the door for them to leave. He walks them to the room in mostly silence because he is now thinking about what exactly needs to be done to keep them both secure but separate. It requires precision, which he has. Since they are bleeding Lucifer can hear his thoughts that would ordinarily be his own, since feelings are usually what they share more distinctly. See, a problem. But at least it's just along the lines of 'what precisely needs to be moved.'

When they get to their room he tosses his journal onto his former side of the room where they removed the bed and put a desk and sitting section, since there was no reason to keep two of them in here. "We should talk." Istredd sounds grave and he is. "Since you weren't given a choice as to how this was made before." Istredd's fault, as they both know. "This is the time we can restructure it." They probably can't break the connection entirely, that might really harm them irreparably, and pulling back to an official Brotherhood mage level would also hurt, but it's doable.

Lucifer gave him no real choice about making the bond, Istredd didn't give him much of a choice in how it appeared. They can do that now. This part is for certain now or never, because it has to all be done or not. The very idea of putting that amount of distance makes him want to die, but he is willing to do it. They're already there.