Derived from the wiki:

"Coal is Bobette's trusty pet rock! She can often be seen helping Bobette take presents to all their friends! Coal may not be as excited about the holidays as everyone else though!"

Coal is a rather stoic Toon, though she often appears grumpy, frequently growling. She generally isn't excited about many things. Unlike the other Christmas Toons, she doesn't seem to care about the holidays. She's usually well-behaved.

This is a HOLIDAY TOON! Holiday toon roles, like Handlers, will be needed less commonly (As they have less comics) and may be double casted if demand is low for hiring. Don't be afraid to apply for multiple roles!

This is a PET TOON! I'm unsure if I WILL choose to cast people for the roles of Pebble and Coal, but i'm choosing to give it a chance anyways.

No particular sounding voice in mind. Simply a pup.