Haha it was a funny dynamic, we had a heavily good aligned party, I was the only one out on my own as "evil". However her whole shtick, as was slowly revealed, was that she had ambitions to take down the leadership of the cult and then replace them with herself and those loyal to her. This meant that the party, who wanted to generally find non-violent means of dealing with conflict, aligned just fine with her own goals of not killing too many of her future minions. So she always acted in what she saw as the best interests of glorifying Her Chromatic Majesty, while still working with the party to stop the cult. Our DM peppered in more dragons and encounters with dragon magic than were in the official books I think, and we all tried to solve them through stealth, negotiation and avoidance. She hated to kill dragons, but if we had no choice but to fight then so be it. If they were too weak to kill us they were culled! She didn't mind stopping the ritual to keep her from ascending because she believed Tiamat wouldn't want the world to end, and just wanted as much treasure and followers as possible. So in the end the cult of the dragon queen became the Church of Dragonology, and her influence on the material plane had a net gain 😋