Curate, connect, and discover
A Reader who gets obsessed with the family. Like, they're pushed into the shadows and instead of agonizing, they understand that yes, that's where they're supposed to be. In the shadows. Obsessing over the family like a shadow in the corner. Making plushies of them to scatter around their room. Pages upon pages of handwritten notes on each member and their lives. Paintings and doodles. Dolls of different materials made to their likeness. Photographies even on the ceiling. Videos and audio recordings. Jewelry made with their hair.
And by the Heavens will they beat up some thugs to death if they try to bother the Bats, because "small flies like them shouldn't make the Family waste their time"
And then, when the BatFamily finally pays attention to them, they really don't know what to do because Reader firmly believe they're where they belong: not as part of the family, but as the shadow always watching from far away. Sure, there is no need to kidnap Reader or anything, they are very willing to stay with the family, but... They are extremely resistant to actually accepting the Bats as their family because, again, it's not their "role in life". The only one they genuinely see as family is Alfred, who they are as a beloved grandfather.
Somehow, the Yandere BatFamily seem relatively normal compared to Yandere Reader.