wait so do all of the in-laws want grandchildren…?
I don't see all of the TWST in-laws pushing their sons to have children. But some of them, due to differing circumstances, might encourage or even require (You) Yuu and their son to have children.
Here's a list of characters that I think may face such expectations from their families:
Draconia Family: Malleus is one of the last known surviving members of the Draconia bloodline, alongside his grandmother, the current queen of Briar Valley. There are only 2 Draconias left, as far as we know. As royalty in the fae world, lineage is crucial for both political stability and the continuation of magical traditions. It would be expected that Malleus, upon marriage, should have children to secure the continuation of the Draconia line and ensure that the legacy of the fae kingdom persists. His family—and the broader fae community—might consider it his royal duty to produce an heir to maintain the kingdom's strength and heritage. Ensuring that they will still have a Draconian ruler should time come to pass.
Shroud Family: The Shroud family carries a heavy legacy of responsibility and duty, they need to continuously manage S.T.Y.X. As keepers of Tartarus/Phantoms, tied to life and death, it’s likely that they would expect a successor. In the case of Idia, his introverted nature might make this pressure even more overwhelming. I imagine Idia might be reluctant to bring another Shroud into the world given their curse. However, the need for a capable heir to continue the Shroud family’s responsibility is expected of him.
Kingscholar Family: As a member of the royal family of Sunset Savanna, Leona’s position as the second prince places him in a complicated situation. Though he is not the crown prince, there might still be an expectation for him to have children, especially if something happens to the direct heir (If Falena's direct line, Cheka is affected). Royal families typically focus on ensuring the continuation of their bloodline, and it does not exempt him from the weight of these expectations. There could be pressure from his family to contribute to the royal line’s security, ensuring the Kingscholar's leadership for future generations.
Al-Asim Family: The Al-Asim family is one of immense wealth and power, with a significant focus on maintaining their influence and control over their business empire. As the heir to this massive fortune, Kalim is likely to face pressure to marry and have children to secure the family’s continued prosperity. Having an heir would not only ensure the Al-Asims remains powerful but would also provide continuity in leadership, safeguarding the family’s wealth and influence across generations.
Ashengrotto Family: Though Azul's family is well, 'normal' in this context, there may be societal or even personal expectations for him to have an heir, particularly if his business empire continues to grow. Azul, particularly his maternal lineage are notable mages in the Coral sea. I imagine there will be unsaid pressure for him to continue his Ashengrotto line. He is a shrewd businessman and Azul may view having an heir as securing a legacy, someone to inherit and manage the empire he will build in the future. His goal to have an heir is maybe more of a personal ambition rather than familial or societal demands.