In this AU, Lawrence died shortly after Lian's birth. A few years later, Lauren remarried. The new guy HATED Lucius for a reason I haven't decided yet, and locked him in the attic. After all, the kids were still just babies, they won't remember him.
Lauren was forced to tell the kids that there's a "scary monster" living in the attic, and that's why there are weird noises coming from it sometimes. That's why the door is locked. That's why nobody is allowed in.
Every time she tells the story, it gets harder for her to hold back tears.