"You didn't need to, I got the message. I'm glad I didn't tell you right away though, you might have abandoned me, and then where would we be now." He was safe as a placeholder as long as he was tolerable and easy. And non-threatening. By the time Lucifer knew, they liked each other better. Istredd's proven exactly why he didn't mention it by now, he is very respectful of boundaries.

I definitely fell in love with your mind first. I thought it had to be obvious when I called it beautiful. That was before Istredd knew that he was developing feelings really, although it probably should have been a sign things were headed in that direction for him. As soon as the bond happened, it was inevitable. Access to that beautiful brain at all times. Impossible to resist.

Istredd is casually referring to his love now because it's clear and they're both aware of it. No reason to be shy about it now.

"You could say that, I would say tempestuous and intense personalities mixed with brilliance and beauty."