The main thing about character development is personality. What adjectives describe your character? How would your character act in a given situation? Say that one of the adjectives that discribes your character is lazy. If that charater was told to take out the garbage, he would still be sitting on the couch 10 minutes later. Since the character's actions relflect his personality, it is important to know what the character would do in any situation.
About the charater's voice: It should reflect the character's appearance and personality. The primary one deciding what the character's voice is like is the voice actor who voices him. Whatever the actor thinks that the character would sound like is what the voice turns out to be. The character's creator should have a general idea of what the character would sound like (the general pitch or accent, for example), the voice actor's interpretation is what affects the outcome the most. Besides, the creator should have an open mind about it, having an exact idea about what you want is way too limiting when you try to get someone to voice the character.
Not literally dead, just no longer interested in Lego or animation.