you and dazai adopted Aya because you're both boys and can't have kids and when she went to sleep you guys had "alone time" but dazai left a bunch of hickeys and love bites all over you especially on your thighs and then aya woke up and walked in meanwhile you were straddling dazai waist and you both were naked but covered up

Aya: dad what are you and daddy doing???

Dazai: ummm uh dad was just letting Daddy take him for a ride.