Abel

From the Castlevania Wiki, the Castlevania wiki

Abel is Isaac's favorite Innocent Devil and a Devil Type. He is at the final form of a Devil, "The End". He is used in the first battle with Isaac, and later when Trevor Belmont fought Isaac and was injured. It is unknown what happened to him after that. He is silver, while Hector's Devil Type is gold, showing that he is the opposite of Hector's Devil as with Isaac and Hector.