Sorry for the wait on this, but! Based on the answer to Dante's questions, I think that Thancred would suggest they try to keep it on a diet without meat and see what happens. That being said, when he returns from the island he will wonder if the little guy isn't a juvenile version of one of the monsters there (the ceiling one). Would there be anything to this, could he maybe ask some Thorne mages about it, etc.? He could also maybe bring another Thorne Summoned who was in the pit and interacted with the monster more to describe it...