Hey! I'm sorry to be so inactive here, but I'm working double shifts from Monday to Sunday and I don't have time :) Anyway, here I present the first sketch of what my Onward AU is.
In this AU, the one who got sick was Laurel. Having a weak body, she died while giving birth to Ian. Until then, Barley would have been as we know him, lively, a lover of magic and a rocker, but when his mother died, this lack of maternal presence affected him, causing a setback in his personality. As time went by, he began to be more confrontational and lazy, more realistic. On the other hand, Ian would adopt that love of fantasy and magic that his brother abandoned after losing their mother.
Wilden, on the other hand, would have remade his life with a certain police satire that would occupy the role of a certain mustachioed man.
Barley would have dedicated himself to music and would have a rock band in which he would be the guitarist and lead vocalist. Ian, however, would drown in a world of magic (and mathematics, of course) that could only be found in his books and games. Barley would have developed a certain contempt for his brother, because deep down he blames him for his mother's death, so he would never miss an opportunity to humiliate or bother him.