Arrax died in the season 1 finale, in a battle with Vhagar and his rider, Aermond. Arrax briefly went rogue and attacked Vhagar, who then went rogue himself and killed Arrax and Lucerys with one bite.

With everything, the point of no return occurs when Vhagar disobeys Aemond and kills Arrax and his rider, Lucerys, son of Rhaenyra. Vhagar is the only dragon left from the time of conquest ...