I saw your post about Masmune and Yuu being siblings AU and can you pls tell us more, I am intrigued in that idea 👀
GOD, OKAY UH. so like my au is technically not at all canon compatible, because of the circumstances of them being brothers, but i do think the idea of them being brothers works wonderfully in canon regardless, because we have no clue about either of their parents, and they're very brothers coded.
in my au the whole thing is dependent on doji being masamune's dad. which i do also like to hc for funsies for canon, but ultimately is nothing more than a fun what if, so bear with.
as for canon, if like... doji's son is still a thing, it would be very funny because then the dark nebula is just half a nepo organization. doji puts his children in there to work for him. masamune gets sent to america because doji doesn't want him in battle bladers, but yuu. well. yuu is like ryuuga's bestie. so he gets to stay. it's also why yuu has so many toys and gets special treatment a lot of the time. until doji shows that he is father of the year and attempts to get his son killed for losing a battle. it would make the gan gan galaxy dynamic a whole lot funnier though, because you'd still have masamune and yuu constantly at odds with each other, but now there's a layer of sibling love behind it. masamune would wreck the garcias. yuu would not be as nonchalant about masamune getting lost in russia. but still they'd be estranged, because they spent so long apart. yuu would probably have little child hatred because masamune didn't have to go through what he did. masamune would be upset on a million different levels for a million different reasons, but he's mostly mad at his dad for doing all this to his brother. SUCH FUN!
in my au specifically yuu and masamune are also age gap (half) siblings, because like yadda yadda doji divorced masamune's mom, masamune moves to japan, things happen. and like there doji has a fling with some woman that results in another child, because he's not been careful. mom of the kid dies in childbirth and now he's left with a gremlin child. masamune would've been like... at least 18 when yuu was born. so that's what we're dealing with in this au. i haven't figured out the exact age gap yet, but it's somewhere around that
masamune was actually kind of excited at the prospect of having a brother. and he does love yuu, especially because he helped raise him. they do absolutely still fight like siblings, and their dynamic is still very much like in the show because that's just their personalities for you (it also explains why yuu is the way he is. masamune is nothing if not a bad influence). yuu always jokes about being closer in age to masamune's kid than to him, and when yuu was younger people thought masamune was his dad.
this got super rambly i'm so sorry, but i just have a lot of thoughts in my head