When Nidhogg is highly implied to be using the Dravanian feature of hyper-adaptability and physical response to the environment to force his children to grow up in a matter of years at most (it takes a millennium for a dragonet to mature, so how do you think he’s been able to replenish the Horde’s ranks multiple times? The down wyverns in the Aery hatch in a small and weak but mature form, ready to swarm you, so a lot of the dragons you've been killing may or may not have been children) though selective breeding which he canonically does bc Vishap’s lore straight up says he’s been selectively bred to be a siege weapon, combined with the fact DRG 60-70 straight up says with Faunehm that dragons cannot resist the calls and orders of their sires or else they literally go insane, lore that’s existed since ARR, and none of this is used to highlight the fact that although Nidhogg’s reasons are just, the damage he has inflicted on the Horde (his own brood) is just as bad if not worse than the Vault and just like the Ishgardians the Dravanian Horde is held in an iron grip they cannot escape by Nidhogg’s rancor, but it doesn’t matter bc the dragons are just enemies that exist for you to kill and you are not to question this unless it's a special named dragon or any dragon that isn't the Dravanian Horde