Cain can only shoot tears from his right eye. This affects certain items: Blood Clot and Chemical Peel have a 50% chance to do increased damage and Technology 2 will prevent him from firing normal tears, even tear-changing effects like Brimstone. Also, the R U a Wizard? pill will cause Cain to fire tears to his right exclusively.
Abel's tears become red and deal 7.5 damage when held by Cain.