3(MLB)

An Au where Gabriel Agreste and Andre Bourgeois got married after losing their wives(Gabriel to death and Andre divorced Audrey when he found out about her cheating on him), it was mostly for their kids as they had just lost a parent and knew the two had always been close.

None of their last names were changed so people had no idea about the marriage or Adrien and Chloe being stepsiblings since their fathers didn't do anything big for their wedding.

Adrien was homeschooled but mostly for fear that he may have the same sickness as his mother(that's how Gabriel explained Emily died) but Chloe finally wearied him down and he let Adrien go to school if they promised to keep an eye on each other.

Natalie is their godmother and spoils them whenever she can so she took them shopping for new clothes to wear when she was told Adrien would finally be able to go to school(seriously, why do the characters always wear the same clothes? Like, I understand wearing the same clothes two or three times a week but they wear it almost everyday and I can only assume that they have multiple versions of the same clothes despite some calling themselves fashion designers).

The stepsiblings arrive at the start of the new year with style and of course most people recognize Adrien since he is still a model but doesn't do as many jobs as in canon since despite everything he is still a kid.

Many got curious about the relationship Adrien had with their schools' 'mean' girl but they found it hard to approach him as he was always with Chloe until the teacher put them in separate groups for a project and his teammates asked him if he was dating Chloe to which Adrien made a disgusted face before saying that Chloe was his sister.

Will Gabriel still be the Hawkmoth? Probably not but it is up to the writer as it is ships, their reactions to finding out they are siblings and anything else that might happen.