Otis Watson is John Watson's younger brother. He's 34 and has a severe mental disorder. Because of this, he can't take care of himself, such as getting a job, cooking, or other daily tasks.
John married Kenny and moved in with him when John was 20 and Otis was 10. Kenny and John have kids. Well since John is now living with Kenny, Otis has to live with Sherlock.
One day, Otis gets kicked out and has to live with John, Kenny, and their four kids, Jude, Cressie, Remus, and Luna. He moves in with them because of his, John, and Harry's abusive father.
Well what happens when John is tired of being the big brother who has to take care of everyone? Will Otis stray away from his older brother and take after Sherlock by living on the streets and doing drugs?