Anytime I think of this character here I think of Thanos. This is the big baddie. A Large alien three times the size of the kids who is super intimidating and scary. I want him to have a calming confident side to him much like Thanos did in Avengers but I also want him to have a hotheaded side too, for when he get's too frustrated. But this voice HAS to be deep, it has to be strong and powerful and it has to be intimidating. Try your hardest to be intense and serious. The lines may seem funny but in all honesty I want him to be naturalistically scary. So don't overdo it, but use his authority/power to your advantage. Make him intense.