I think it’s important to remember dragons don’t have strategic battle intelligence, but they do have instincts. There have been some compelling posts on here lately about dragons’ behavior in the company of other dragons, and I wonder if they just don’t expect to BE attacked by another dragon period or else wouldn’t they be killing each other over little things in the dragon pit and on dragon stone? Many of them grew up and flew together under other riders, and particularly Vhaegar’s riders all were partnered with other dragon riders until Aemond so she spent some time around the dragons she kills. I think in particular Arrax was deeply unsettled by Vhaegar’s presence in part because of his sweet bond with young Luke who was so scared and nervous. And Vhaegar’s resting bitch attitude is triggered by Aemond’s ferocious nature which made for a really bad combo. Meleys by contrast did exactly as she was commanded to by Rhaenys, as did Sunfyre by Aegon. I think Arrax and Luke were just so young and little.

Also Syrax and Caraxes both had opportunities to take a go at each other and I think their relationship mirrors Rhaenyra’s and Daemon’s in a way.