Kyle was originally a vicious, aggressive, ferocious, and monstrous blue creature that even Gru had trouble controlling. At times he would attack Gru but despite this he also seemed to be easily spooked and appeared frightened whenever Gru or anyone else opened the secret lair and also ran away from Agnes, unused to the fact that she thought he is cute instead of trying to avoid him. When Agnes, Edith and Margo first arrived, Kyle greeted them by snarling but he gradually warms up to the girls, especially Agnes and started sleeping with her at night. Although he seemed exasperated when the three girls dressed him up, he nevertheless develops an attachment towards them just like Gru did.