Looks like a good draft :)

I agree that Karen would be the first thing from canon to happen.

I don't think it should happen immediately, though. I think we should do some worldbuilding and relationships first. I think it would happen pretty late, actually, at least several chapters in.
- After Matt is settled down in Fisk's ownership
- After he establishes a routine and has a "normal life"
- After he met most domestic slaves in Fisk's manshion, probably
- After the first 'office meeting' happened (I imagine that as a chapter)
- After the meetings became something of a routine for Matt
- After Matt's entanglement with Weasley started, maybe because of all the meetings

So, I would trickle things pretty slowly. What do you think?