I honestly don't remember what I or Fédora knows about Erat, but Fédora will tell Rilcheaux what she knows.
I seem to remember that he had something to do with what happened in A Covenant of Doppelgangers, but a quick search doesn't show he was anything but namedropped by Carmen.
Regardless, he's still a scoundrel through and through, and he's had some shady dealings with Barcelona (I think). And any shady dealings that impact her can be traced back to her mudák of a husband Vulcanus.
[color=blue]"That is a good idea. I'm sure you've had experience in negotiating, and I would like to see how well you do."