Elderling Creations Theory (Spoilers through all the books and Dragon Haven)

['thul]

CoD-level spoiling

It would appear that at least some of the theories 'thul had on Elderlings and how they come to be were true. For an Elderling child to be viable and alive at birth it requires a certain level of development. Thus it was not possible for Malta/reyn to have a living child until after their changes had progressed to a certain point. Had Tintaglia not abandoned them, that point would have been reached sooner.

It seems to 'thul odd that children born to Elderlings require the stuff of dragons to live at all, so they theorize that fully formed Elderlings (ones that have been finished by dragons in all aspects) possibly have more viable children, though the children will need dragon proximity to become full elderlings themselves.

It was certainly verified that not only do Elderlings prefer warmth, but in fact require it for their transformations to get to certain points. The water that Thymara & Rapskal bathed in at the revival of Kelsingra might indicate that they also need water for their bodies to fill out more quickly, though this is uncertain. Considering that Elderling bodies often are bigger than human bodies, they need more fluids to keep them fully stocked. It could be drunk, but it seems absorbing them directly through the skin is quicker.

As for Thymara herself, 'thul believe that she will always develop more willowy than many of the other Elderlings. This is partially due to her gender, but more due to her wings. For her wings to be viable for flight, her body needs to be quite lithe and light, otherwise the wings would need to be gigantic. It is clear that she would need to develop much more to gain flight, as well as practice much like Rapskal said. Not only does she need to grow her wings larger, but she needs to increase her muscular strength in the back and upper chest, the muscle groups that power the wings.
'thul believe the first forms of flight will be short gliding, allowing her to jump much further than others and drop further harmlessly. Then it will be short distances, before eventually (with practice) going further and further.