This is Boso's maid, Emma.
She's not a very good person so it makes sense she's super into Boso.

He was feeling neglected and angry that Olivia (is wife) was spending more time and attention with Harold and Frederick (their kids LMAOO) so Emma took advantage of that and sweet talked him into having an affair with her. Olivia found out and she stayed with him for their kids until she couldn't take how Emma started to treat her. Boso threatened to hurt the kids if Olivia left with them so she left by herself thinking that Boso wouldn't hurt them (like he promised).

Well he lied LMAOOO and Emma got creepy about taking care of Harold and Frederick, like acting as if they were her own kids and Harold told her to f off and so Emma started to hold a grudge towards him. She would lie about him hurting her and causing trouble just so Boso would step in and defend her.

Harold decided to run away with Frederick and one of the house staff he got close to while growing up. That's a whole other story cuz they had a secret relationship and were boyfriends.

Harold was 18 and Frederick was 8 when this all happened, but Emma found out about what Harold had planned and she told Boso. He didn't like that at all and caught Harold and his boyfriend before they could go get Frederick and shit went down :(. Harold had to watch his bf die in front of him while Emma helped Boso, she went to attack Harold but he ended up escaping.
Its a lot of backstory for a side OC, but the song fit her lol