Had been having trouble deciding on this one - then I read the very excellent Desdaemona by Ben Macallan (which, if you haven't read it yet, do so, pronto!) - so, answer sorted!
The main interactions being between lead chap Jordan and the titular character Desdaemona - deliciously argumentative and snarky, with some growing affection and nifty surprises thrown in for good measure. Also worthy of note are the interactions between Jordan and his brother Asher, and then the trio together, being pure gold. Could have happily read more of them.
