From the publisher:

BROTHER & SISTER 2-PACK
Grave is careful and in control. His Dragonheart attack is tied for the fastest in the game. Sometimes he can look at your hand cards, other times he counters whatever you tried to do. His sister Jaina, by contrast, is fiery and reckless. She can damage herself to buyback her attacks, and to change her mind mid-combat in desperate situations.