...I really, really love your metaphors. That all makes perfect sense - especially when you factor in just how much Illyria talks, for a derisive demon god. I always thought she went on rambling speeches because that's what Fred used to do.

I think she was drawn to Wesley, initially, because of how strong Fred's feelings for him were - and then she began to understand those feelings, and truly share them. Wesley is the catalyst for a true blend, their shared point. The cast, perhaps?

In the After the Fall comics, we see Illyria spontaneously turning into Fred - she can't control it any longer. Perhaps because, as time goes on, Fred's presence grows stronger within her.

And, naturally, the first time we the reader see this happening is when Illyria sees Wesley again.