Blue is cruel dog who was never loved by anyone.He dislikes pet dogs due their easy life with humans.He manipulates young puppies to serve him, as he shows them care and praises at the times. However, he turns easily violent when angry. If the puppies try to resist his orders, he always makes them feel guilty by mentioning that he saved the pup and that the pup would be dead without him. Blue attacks and threatens to kill the pup if the blame doesn't work, sometimes even fulfilling the threat without any mercy.

Japanese voice for reference https://youtu.be/1uTGHQSlJLg?t=18m26s