Linking Lives / Book 12 / The Life Series / Supernatural Season 13

Ness Singer-Winchester had been pregnant when she had the Mark of Cain, leaving her and Den's children, Aiden and Amara, with effects from the mark that they didn't fully realize until recently. Baby Aiden had always had the ability to sense evil, no matter what the creature. Amara had always had the ability to tell when someone was lying to her. Lucifer himself told Crowley who told the British Men of Letters that if both Aiden and Amara had had a near death experience at the exact same moment that the two twins would be linked, unleashing their powers, and also causing Aiden to grow up to the age of Amara, who's age had been accelerated before due to being possessed by the Darkness. Now that Aiden and Amara are linked, Aiden had to grow up from being a toddler to being Amara's age. And now both twins are set on learning about their new powers and how to control them. While Dean and Ness are happy to have them together as a family, they're also very worried about what could happen to them, and they had never wanted this life for their children, but knowing that they won't have a choice anymore.
Brandon Davies is also former British Men of Letters that had been on the run from the Brits after Ketch killed his father Mick. Brandon got justice for Mick when he killed Ketch, but when Ketch comes back from the dead, Brandon will have to face the fact that they may need him, though he won't forgive him, and neither will the Winchesters.
Brandon and Amara are also closer than ever.
All of this while welcoming Jack into the family and wanting for Cas to come back and trying to save Mary and Jack from the Apocalypse world, it will be a very busy year for the Winchesters.