They're like Ridley Scott's Xenomorph (Starbeast in early drafts). They can have sexy queens/kings that lay the eggs with some sorta unexplained sexy times. Orrrr they can turn out eggs on their own, such as when the singular Xenomorphs do that to people in one of the Alien movies.

As far as their appearance goes, it's been revealed by Endwalker that getting enough aether and aether of a certain purity results in appropriate dragon babies. Otherwise they come out lookin' like tiny Vouivres. However, instead of being born supremely adapted for flight as that's what vouivres are said to be in dragon terms, they're malformed, lacking proper scales and are inherently hostile. If they don't be all dang ole stillborn in their mushy goopy egg plasm.