I think a cool new angle for pets would be a few new species. Here are just a few that I think would be cool:
Spider - Arcane ability could be to wrap up an enemy in silk, immobilizing it
Squirrel - Gives owner extra storage (loaded up in cheeks), has low damage, but can attack faster/more frequently
Lion/Tiger - Paw slash with good damage
Bear - Again, good paw slash with high damage
Snake - Venom strike
Cheetah - increases character's speed
Scorpion - again, venom strike
Croc/Alligator - Improved defense
Rabbit - Come on, someone there is a Monty Python fan...

Love the game, guys!