On Lucifer Season 1 Episode 11, Lucifer took a knife to his hand to test his theory that Chloe is his Achilles heel. He could have just asked all of us instead, since that little tidbit of speculation has been blaring like a foghorn for several episodes now.
While this reveal isn't necessarily surprising, it certainly is intriguing, especially now that Dan is privy to Lucifer's vulnerability, so to speak.
And Maze and Amenadiel? Didn't see that one coming.