Just my two cents here:

I uhm... don't really like the idea of having some super powerful eldritch horror creature with no real weakness to balance out it's overpowered abilities just "lurking" in the shadows. It's not even an accepted race, so if it ends up joining the RP whats stopping everyone from making their own "primeval" vampire god-monster hellbent on ruining some guy's day? Or would the current subject be the only one allowed because having a ton of disgusting evil monsters running rampant would derail the RP? If so, where's the fairness? Why should Doctor's overpowered animal be the only one around? This would be an interesting concept if utilized by a GM to drive the plot further down the line, but just letting one player have complete dominion over all of the other characters with an arguably lazy creation that doesn't even bother detailing it's history in the slightest? Letting that thing into the RP in it's current state would be an affront to everything this RP is about anyways; The interactions between the players and various factions.