Yandere laios and the gang with a siren or witch darling that live in the dungeon cause she can't stand the way people behave around her (it could be people above are afraid of her power as a witch or siren or her monster/demi human race's beauty is to much for them to handle)
I kind of love the idea of siren darling because of how absolutely fed up with Laios's shit she would be. She would constantly be bewildered by how this bumbling tall-man keeps managing to make it down to level 4 without being mauled. It's obvious to her that he means well, but there's a reason that she chose to live in the dungeon rather than contend with full-blooded humans on the surface.
On a deep level, she would appreciate that Laios understands her. A lot of Laios's interest in monsters comes from the alienation he's felt from those around him growing up. In another timeline, perhaps he would have chosen a life in the dungeon himself. However, his obsessive interest in her (and encyclopedic knowledge of sirens) is ultimately off-putting to say the least.
Not to mention his horrific singing in an attempt to bond with her.