I suggested Kali's parents simple as an option - not saying they're a "good option", but an option compared to the existing choices based solely on the characters we currently know? Most likely.
A quick and dirty comparison:
Father is massively wealthy and influential. Has his fingers dipping into multiple industries and has one of the leading tech businesses in the world. Married to one of the oldest half-elves in the world, doesn't appear to be abusive.
Step-mother supports Kali despite early disinterest from Kali. Has sex with her husband(which is why Lucy moved) and doesn't openly seem negative to it. Was concerned when he was shot, suggesting some level of care plus the sex life is important framing because they sound like an actual couple. Supports / suggest the MC shelter and save elves using the money gifted to him by the father.
You have a literal power couple of the MC/Lin but at a national level. Not only does he like elves, he's married to one. Not only is she common born, she's a half-elf. Are they worthy of leading? Not necessarily, but at least the father has some experience in leading a company and she has a shared foundation in the common elves and their mistreatment.
MC/Lin:
Not a ton is known about him prior to moving and inheriting the hotel. The hotel lost much of it's value that it was down to one slave/maid and the receptionist. He turned that into a thriving local business. Aaaaand that's it so far. He's traveled, he's experienced, but he has no real connections to change anything. The false queen turns to him for help and how'd that go? Maria's story events? More of the same. If Kali wasn't staying at the hotel, he'd be even worse off than he is for those he loves. Lin? She's a common elf with a huge heart but is unique about her that would help tie folks to her? She's lived a relatively sheltered life, wasn't abused by slavers, wasn't forced to work the streets. By comparison to nearly every other common elf we've encountered she's had it really good.
Again, just tossing ideas out. I'm not saying my thoughts are gospel or correct. I enjoy the discussion and bouncing ideas around.
My issue with this is the dungeon hasn't been used to humble anyone. Assert a level of dominance, awaken the girls to other sexual ideas? Sure. As a form of detention for bad behavior? The MC doesn't / hasn't rolled like that.
Any of the girls who love/trust isn't high enough can literally say no and walk away, nothing about the dungeon is forced. I can't recall a single event there that is a form of discipline beyond dragging out if the girls are allowed to cum or not. That's really the only thing about it, delaying the gratification. Unless I'm not remembering correctly, but if I am, then this won't be how Slyvia gets humbled unless Runey specifically decides to change it for her.
Besides what could be more humbling than finding out your queen sent you to a foreign land to be raped/enslaved/killed off, only to return home and be locked up and abused. I think Slyvia knows exactly where she fits into things, she's just afraid to confront it and her acting the way she does is just that.
As for K-dad and his new wife, I would have to oppose that on every level. Yes, he can run a company, but a company is not a country, and simply turning a profit is not your main goal, it is caring for your people, and none of their events really show them doing that, or thinking about things much beyond the money (oh, and personal desires). Then you have the previews of what is to come for next time, and I am really concerned for Mariella.
They don't really show good judgment, and don't seem to care who they have to hurt to get what they want.
I also realized that I forgot to include humans and half elves last time, since I also think the only way forward is for all people to come together. And honestly, President Lin makes a lot more sense anyway.
And no, I didn't mean that the MC would use the dungeon to humble her, just that doing that would help, the IDEA of it more than anything else. She needs to be shown, that she is NOT better than anyone else. She is the same.
Slyvia doesn't really fit either. Assuming you go the love route, she learns the hard way she was tossed away like garbage. She knows there are assassins out looking for her. She wants nothing more than to sit at home, away from everyone else watching TV. She pushes everyone away, even Nia who she conspired with to get freedom in the first place. She accepts a job doing work she feels is beneath her. She accepts sex with a person she feels is beneath her. Her defensive / sniding comments shield her from a lot, but it's wavering against the harem/MC. I think she's humbled, in the most humiliating way she could have been, and her coming to accept that is what brought her to accept the job / MC sex. I don't think the dungeon will have the same significance that it held for Felicity/Emma in that regards compared to what she's already started doing.
We need more Slyvia and Kali/Maria events
And yet she STILL complains about having to work even a little bit, rather than sitting on her ass all day and night, watching TV. She is lazy and entitled.
I don't deny that she is getting there, but she is not there yet. She still thinks that she is better than the other elves, she still thinks that she is too good to work, she still thinks that she is better than the MC too, the person who has gone out of his way to help her, in every way possible so far, without whom, she would be in serious shit, if not dead.
Knowing him, I say he would use headpats to change the world - and it would even work.
If you are a good girl, I will give you nice headpats, if you are a bad girl, you get hard buttpats, and if you make Lin unhappy, I let Android do them...