"Hey! This beast isn't my Beast Pet" said Damian, who didn't want to have to take care or have the responsibility of looking after the Monkey Beast.
It had become big, was very playful and a hassle to deal with, especially since Damian didn't understand its reasonings and had no way to control it or ensure that it wouldn't switch at him randomly one day.
There were too many risks with keeping a beast around and becoming friendly with a beast, since most would have a hatred for humans that they cannot control and could also become wild at any moment.
However, Damian also had no choice but to rely on the beast in his current situation and after recovering and paying it back with the Moose Beast's body that would be very beneficial for a beast, he was planning to part ways and stay away from the unusual beast.