" - It's possible with most dragons in the swath of the multiverse tied closest to the Astral Sea. Relatively rare, but, there've been a few cases."
"For one - a few rare spells can permanently alter someone's form. That's insanely hard to do to a dragon, but you can stack effects, and a newly hatched wyrmling won't be as naturally resistant to magic, nor as capable of actively resisting. And though polymorphing a wyrmling and abandoning her on a backwater would be weird, it's a big multiverse."
"Also... Some dragons can just change shape by themselves, naturally or through magic - and you could in theory get a wyrmling to shift to one form and forget how to change back. And the outcomes of reproducing while not in your natural form are weird and complicated, but most dragons who've shifted naturally will produce magical offspring that take the shape they're in at the time. Usually that's half dragons, but two dragons have ever reproduced together while neither was dragon-shaped - they'll produce a wyrmling with a non-dragon default shape."
"Though that gets very weird if they weren't shifted from an innate power - I've only ever heard of that one coming up with prism dragons, which are a rare kind of dragon known for entertaining themselves by manipulating societies and people, which can't shapeshift without external magic."
"Dragons that can shift into a humanoid without spells... Of the true dragons, that's silver, bronze, gold, all the imperials, and dungeon. Silver dragons are the big ones known for sleeping around, though honestly dungeon dragons are better shifters and more inclined to it, they're just rarer. There's others too - havoc, nightmare, dream, and astral of the outsider dragons, and in theory a sinborn dragon could change shapes, but those can't actually reproduce normally without very significant magical intervention."
" - Anyways, an astral dragon would be more likely than most others to end up in a weird corner of the astral sea, but Ellie doesn't super strike me as part outsider dragon? Those tend to be - kinda obvious."