I'm a big fan of Medb and that final scene was the gut punch I did not see coming.
I'd be good with the MC seeing a trap, warning Medb and helping her escape it, then being hunted by the third party so they both flee Neverwhere to a different world (neither Earth nor Alfheim) - in an attempt to avoid those hunting them.
This would give them both a reason to depend on each other and the opportunity to build a bond that neither society (Alfar or human) would really allow - given who they are.
With that bond and the obvious closeness of the MC and Medb for each other due to their escape and evade, depending on each other, eventually finding a portal back to Alfheim and going to the Alfar capital would take on an entirely different tone that the MC's first meeting.
Proof of a third party, added to Queen Mab's ability to 'read' and be 'read' by the MC, revealing the depth of the growing bond, their closeness and the MC's sincere desire and efforts to protect Medb and return her to the Alfar could even earn a measure of approval and acceptance that this Human was truly different.
It will be hard to wait for Ceolag to give us the next chapter of this great AVN!
Cheers!!