First Generation Dray
I always liked the first generation dray, because they left a lot of possibilities what could become of them. In our campaign, not all of them were lured to New Giustenal by Dregoth's illusion of the Spirit of Kragmorta. They found out that Dregoth was behind it, and while some first generation dray then voluntarily sacrificed themselves to the undead dragonking, others decided to flee. The only area they could flee to was the surface, where they knew they would be hunted - if they ever got there in the first place.
At first the plan was that only one party left while others maintained the illusion that the first generation dray were still to stay in Kragmorta. But then panic broke out and Mosak became the somewhat involuntary leader of the dray refugees. In order to survive, the first generation dray have to rely to a great part on the help of surface dwellers. This makes both parties very uneasy. In our campaign, this was negotiated by the player characters who helped the dray escape and who keep protecting them from Dregoth's wrath with the help of druids.
But there are many options, what you could do with these creatures. For instance, they could be played less subdued and more angry. First generation dray could start to actively sabotaging Dregoth's plans, especially after his potential setback in 'Dregoth Ascending'.
There is also the possibility of these ever-mutating dray to develop interesting mutations that could turn into adventure material. Are the dray in the process of evolving into a new distinct race with a novel combination of powers? Are they changing back into humans or reptiles? Are there dray individuals who turn against the life-style of the kragmortan society and try to build an existence outside of Guistenhal e.g. as an adventurer?
If the first generation dray decide to escape Dregoth, what are they going to be? A tribe in the style of the slave tribes or bandit states? Will they hide in a camouflaged oasis? Will they flee to somewhere where they hope Dregoth cannot reach them? Who could have an interest in the first generation dray?