[This is just a fanfic idea I'm working on. ;) ]
It takes place in the ABO universe in a corrupted future. Takemichi is 24 years old, while Hanma is 25 years old. Takemichi is an Alpha Lupus. Hanma is a regular Alpha. Kazutora is an Omega Lupus. In this criminal underworld society where the three brothers now live. The underworld is oppressive and sexist towards the Omegas. The Omegas of the underworld are raised only to obey, marry and procreate. When wolves reach 15 years of age, they discover their wolf gender and enter puberty until the age of 18, when they will begin their first heat. Kazutora turned 15, but on his birthday there ends up being an attack on Takemichi and Hanma. Kazutora, trying to save Takemichi's life, ends up suffering an accident that leaves him paraplegic. Takemichi and Hanma are overprotective of Kazutora, and Takemichi blames himself for Kazutora's paraplegia, being dominated by his independent wolf.
(The fanfic explores the underworld of Tokyo's mafias, and the oppressive treatment of the Omegas. And how Takemichi and Hanma tried to change Kazutora's fate.)