Hau and Lillie have a pretty complicated storyline in mine regarding their children, so I’ll explain it as best and simply as I can.
After they get married, Lillie’s dream is to have a child with Hau. Specifically, she wants to be the one to get pregnant with said child. However, the two end up having many difficulties with this. Lillie struggles to carry a child to term, suffering multiple miscarriages. Despite going to multiple doctors, they can’t seem to find anything that might be the underlying cause behind Lillie’s fertility issues, so she keeps trying in the hopes of being able to have the child she’s dreamed of. It’s difficult for both her and Hau, but her husband is nothing but supportive during this rough time period. Eventually, Lillie is able to carry a child past 6 months and she and Hau are tentatively hoping that this will be the one. Sadly, their son, who Lillie names Echter, is born very prematurely and only survives for 5 days after his birth. After losing Echter, Lillie comes to the conclusion that, for whatever reason, she just can’t have a healthy child and she and Hau decide to take a break before deciding how they want to move forward (be it adoption or Hau being the one to get pregnant, as they do still want children.)
About four months following Echter’s death, Selene, Gladion, Hau, and Lillie, along with some other members of the new Alola League, hear about an underground lab run by rogue former Aether scientists and make it their mission to apprehend them. When they raid the lab, they discover that these scientists had been conducting experiments on Ultra Wormholes using a young boy they had as a test subject. This boy has the amazing ability to open and close Ultra Wormholes with just his mind, hence why the scientists had adopted him when they heard rumors of his abilities from his foster family. In lieu of his real name, and in order to not simply call him by a subject number, many of the scientists in charge of raising him and studying his abilities started calling him Weiss, due to his pale coloring. With nowhere to go now that his only home had been dismantled, Hau and Lillie realized this might be a sign. Here was a child in need of a good home and loving parents, and here they were wanting a child so desperately. Thus, Hau and Lillie end up adopting their half-alien psychic son, Weiss.
About five years after they adopt Weiss, Hau and Lillie decide to have another child, but knowing Lillie’s previous fertility issues, this time Hau is the one trying to get pregnant. They are able to have a daughter, Hina, together and they adore her dearly (as does her big brother Weiss.) Then, another five years after Hina’s birth, and unbeknownst to Hau and Lillie, a malevolent dark wizard who has plans to use magic to control Ultra Beasts to take over Alola decides to conjure himself an assistant/familiar. As a necromancer, this evil mage decides to find a useful soul to revive. It just so happens he decides that the lingering spirit of a baby mage (note that Lillie is a light mage) he discovers is the best option for him. Using his magic, the evil wizard (who… doesn’t have a name yet), creates a sort of homunculus that resembles what the spirit would have looked like had he grown up. As Echter would have been 10, he is first revived with the appearance of a ten year old, though his artificial body does age. Using magic, the evil wizard implants his new servant with the knowledge he needs and sets him to work as his assistant. Revived!Echter has no memories from before his revival, of course, and though the evil wizard is often cruel and neglectful towards him, he knows no other life…. that is until three years later when he meets Primrose and her friends. Thus begins the little ‘side-plot’ that many of my Alola fankids are involved in.