On Supergirl, Mon-el decided to have a heart to heart with his mother, Queen Rhea, who seemed to be in competition with Joan Crawford for a Mother of the Year Award. When Mon-el asked her to stop sending bounty hunters to kill his girlfriend, Queen Rhea basically pulled out her version of a wire hanger and instead knifed Kara in the leg with a kryptonite sword leading Mon-el to relent and join her and his father back on their ship in order to save Kara's life.
With Mon-el basically agreeing to be the future Daxamite king, he thought he'd suggest that they take a more communistic approach to their rule but Rhea wasn't having it and she slapped him in the face and sent him off to a cell to think about what he'd done for the next four years or so.
When Kara and company teleported on board to save Mon-el from his bummer parents, his father King Lar Gand had a change of heart and sent his son on his way back to earth, seeing that it was what would make him happy.
With Mon-el off the ship and back on his beloved planet Earth, Queen Rhea stabbed Lar Gand to death for his betrayal, so it's safe to say Mon-el has not seen the last of his charming mother.