Young Justice Episode 20 Coldhearted Episode Title:Coldhearted.Episode Description:On his sixteenth birthday, Kid Flash finally finds out about Superboy and Miss Martian being a couple, and is disappointed when he is tasked by Batman to deliver a heart transplant to ten-year-old Perdita, who happens to be next in line to inherit the throne. Meanwhile the rest of the Team is sent to join the Justice League and destroy flying fortresses causing nationwide snowstorms. He later realises that the mission was his best birthday gift.