Grace.

This is the plot. Kinda ruins the story so, sorry? I guess. So don't read if you don't want spoilers(?) the first para should be okay but the rest, yeah don't read that 😂

Reader (Katrina) is Demon cross angel, Michael is her violent ex, she got with dean when Cas brought her to him when Cas found her almost dead cuz Michael's a dick. Dean and Katrina had a daughter, Kat told dean the kid was Michael's. Dean got drunk and cheated came back and beat the shit out of Kat so she left everything behind.

Michael is back and Dean goes to collect her to keep her safe. She meets her daughter (properly), her mother throws her under the bus and Michael shows up at the safe house and threatens to kill Jack and Grace (their daughter) obviously Kat is not impressed and her angel side takes over and wipes Michael off the surface of anywhere.

She scares her daughter to the point of she can't hear her mother's name and can't read a book her mother wrote. She has to leave to protect her family which is when (trigger warning) she kills herself because it's safer for everyone. Cas finds her body and has to tell dean which at the point tells Grace and the mourn her death. Grace becomes annoyed she didn't tell her mother how sorry she was and that she loved her when she had the chance so leaves to Heaven where she (inevitably) becomes emotionless and a good soldier.

She is then assigned to her dad who's been struggling with the losses. As she cannot intervene, Dean loses it and sells his soul to be with Kat which doesn't happen because Grace gets involved. She goes home with him to make sure he is okay and then doesn't leave. She then falls for Jack and they start looking after dean during his fight to stay away from alcohol. She stays until she finds out Jack is dead (S14 finale for reference) and apologised to her dad but leaves again. Dean mysteriously gains a grace and joins his daughter in heaven. The end