The Rattle Griffon is not a purebred dog. It is a cross between the Brussels Griffon and the Rat Terrier. The best way to determine the temperament of a mixed breed is to look up all breeds in the cross and know you can get any combination of any of the characteristics found in either breed. Not all of these designer hybrid dogs being bred are 50% purebred to 50% purebred. It is very common for breeders to breed multi-generation crosses.
American Canine Hybrid Club = Rattle Griffon
Designer Dogs Kennel Club = Griffon Rat Terrier
Designer Breed Registry = Griffon Rat Terrier
Scamper, the Rattle Griffon. He's ? Brussels Griffon and ? Rat Terrier
ACHC, DDKC, DRA, IDCR, DBR