Monster represents Caballero's father, and is meant to be able inspire both comfort and fear, as Caballero's real father did when he was young. In discussing the character with Rodis-Jamero, Caballero came to realize Monster didn't accurately represent his father. As you can see, the new Monster (top right) is less colorful, not quite as scaly, has less defined claws and a drastically altered head. In Caballero's words, "He's scary, but there is something that attracts you to him – something that makes you want to play with him, help him, even though he's a beast who could fly into a rage and kill you."
Naturally, some won't approve of the change. Responding to a negative comment on PlayStation Blog, Caballero explained that the original Monster combined elements of his father with playful elements of his own dog. "I had to be honest," wrote Caballero, "and admit that Rhino [the original Monster], as much as I liked him, was more my dog than my father."