Small, random questions about RotE that still bother you (spoilers all RotE books)

[Nuytsia]

Here's another one!
In Assassin's Quest, when the Fool touches Fitz with his Skill fingers and Kettle joins them, Fitz thinks:

"I was the Fool and the Fool was me. He was the Catalyst and so was I. We were two halves of a whole, sundered and come together again"

I found it a bit strange that he says 'he was the Catalyst and so was I' ........ he seems to be saying at first they are exchanging places so you'd expected him to say something like 'he was the Catalyst and I was the white prophet'.....but he says they are BOTH the Catalyst?? Is that just a weird way of expressing what's going on, or is there more to it?