Soulmate au but Shiro and Ulaz are soulmates but Shiro is with Adam.
Adam doesn't have a soulmate, he has no red string of fate but Shiro does. However Shiro doesn't care and ends up getting with Adam and they end up engaged. This au still follows the canon so Shiro ends on the mission and yada yada.
Shiro and Ulaz meet again when Ulaz breaks onto the castle. This is where Shiro realizes that they're soulmates. So instead of Ulaz dying, he lives and stays with the Paladins. Shiro ends up in a dilemma because Ulaz is both sweet and attractive but he still loves Adam.
Cue ✨️poly✨️ stuff
Now, it's not something that happened quickly because one, Adam is incredibly confused and two, because Ulaz is also incredibly confused. Shiro is just praying it works out. It does but that doesn't stop a week or two worth of confusion. Adam is just confused as to how an alien is Shiros soulmate, especially an alien that might be a few thousand years old. Ulaz is just confused by how Shiro is Keith's brother but Adam is Keith's parent even though Adam is younger than Shiro by a year or two.
