At first he thinks he's talking about Ciri, which would make him defensive, but stringy is not a comment anyone would make about her. Istredd guesses instead that it was Jo, who he met on the back of the turtle, but he doesn't know well enough to say for certain. She was grieving Dean, that was when they still thought he was dead. She seemed like a good woman, if brisk in her grief. Enough to talk to him when injured despite her feelings.

That group from what I can tell are all monster hunters of some kind. It isn't a surprise Geralt fell in with them. From what Lucifer said, Dean and his brother were hunters. Just like Geralt. Ciri must be close to them as well. He notes that for his own knowledge.

Istredd lets him rant about the wings. He knows that Lucifer is very proud and serious about his true self and heritage, and that is all fair and reasonable. I can see how that would be upsetting, an enemy given the appearance and skills of your kind. He doesn't know why the Singularity would do that other than it might have a sense of humor. Or it might be his close relationship with Castiel shining more than his hatred of Lucifer and Michael.

But Lucifer barely has access to his angel self. Feeling bitter about it is normal. He pats Lucifer's shoulder in solidarity. I wouldn't hold onto it though if you can help it. It's only going to upset and hurt you in the long term. Upset like he is now, hurt as in having another fight. Pointless. They have bigger things to worry about.

Isterdd shakes his head. No, they're more like a hybrid of things. Human and something else. Istredd has only heard the witcher details, he hasn't asked Geralt himself for confirmation. Nor does he plan on it. He isn't a big fan of mine. Or any mages, really.