- Aria: Monsters and humans used to live without a divide between them.
- Aria: The two worlds naturally overlapped, and you could freely move from one to the other.
- Aria: Monsters and humans were on seemingly good terms.
- Aria: But they did not truly accept one another beneath the surface.
- Aria: Because of that, it was frowned upon to surround yourself with monsters if you're a human, and vice versa.
- Aria: But it wasn't exactly disallowed, so many monsters and humans adapted to this lifestyle.
- Aria: My family was one of these, we settled in a humble small village around here long ago!
- Nino: Oh, really?
- Nino: How was the life there? Wouldn't you have had a hard time because of the other monsters?
- Nino: Also this tea is kind of bland, sorry.
- Nino: ...Not that I don't like it, of course, haha--
- Aria: Oh shush, I just ran out of sugar! It'll taste better with the muffins!
- Nino: Fine whatever you say.
- Nino: ...Oh uh! Sorry for interrupting, please continue!
- Aria: It's alright! As long as you're listening!
- Aria: So anyway...
- Aria: It was a comfortable life in a quiet place, away from the never ending political disagreements between monsters and humans at that time.
- Aria: Although, like you said, it was indeed hard to be a human in a majorly monster populated area.
- Aria: I never had any friends just because I was human, and sometimes the rest of the monster kids shunned me...
- Aria: But I wasn't lonely! I had my family with me.
Nino: Was the war mostly fought physically, with soldiers? Or was magic involved? Who started it? How did it end? What was the goal?
- Aria: Well, I guess I wasn't lonely until after the war.
- Aria: That was when the divide between the two worlds came to be.
- Aria: The divide ended the war, because it made moving from one world to the other impossible to achieve.
- Aria: Not only that, but it trapped everyone inside with a strong dome barrier.
- Aria: I'm sure you know what the dome is, right?
- Nino: Of course I do!! It's the layer covering the sky!
- Nino: I wouldn't forget what I see every day, you know!
- Aria: O-okay sorry, I'm just making sure!
- Nino: Well, just keep going. I'm listening.
- Nino: Actually, wait, I have some questions...
- Nino: Was the war physically fought? Was there magic?
- Aria: Of course it was physically fought, with soldiers from both sides...
- Aria: But, uh...
- Aria: Magic?
- Aria: Nino, you big goof.
- Aria: Magic isn't real!
- Nino: Hey don't make fun of me!
- Nino: I'm just, uhh, refreshing my memory. Yeah! Totally.
- Aria: Suuure, sure.
- Nino: Something tells me you don't believe that.
- Aria: You're just too silly sometimes.
- Nino: >:[
- Nino: Well, I have more questions.
- Nino: Who started the war, and why?
- Aria: Nino, I don't know everything!
- Aria: I'm sure the web of political disagreements between monsters and humans is something far too daunting for me to try and figure out!
- Nino: Fiiine okay, that's fair I guess.
- Aria: So, moving on...
Aria: This has defined this world's history.
- Aria: Because of the death of the previous prince in the war, and this world nearly dying as a result of it...
- Aria: Everyone was trapped, and everything was left in shambles.
- Aria: Until the new prince rebuilt it all.
- Aria: And then, he made a promise to everyone inhabiting the new world.
- Aria: "You will not be harmed again", were his exact words.
- Aria: He did not allow humans to be in this world anymore.
- Aria: And this new rule is what defined this world's history.
- Aria: Every remaining human stuck in the monster world got eradicated.
- Aria: Even my own family.
- Aria: I thought I was a goner too, but my disguising ability came in handy.
- Aria: And thanks to it, I'm still surviving even now.
- Nino: ...
- Nino: I'm really sorry to hear that, it must've been awful.
- Aria: It's fine, please don't be sorry!
- Nino: I really don't like seeing you sad like that, I-I guess.
- Nino: Sorry if that's a weird thing to say.
- Nino: Your face is the face of someone who should only be smiling.
- Nino: Okay THAT was definitely weird, I'm sorr-
- Aria: Nino, stop apologizing oh my gosh.
- Aria: I'm not sad, it's just because I'm remembering tough times!
- Aria: But it's alright now, I promise.
- Aria: Because I'm not lonely anymore!
- Aria: I have Kotori, and now you and Five...
- Aria: So don't worry about it at all!
- Nino: Well if you say so... But are you sure it's really fine?
- Aria: Yup!
- Aria: I would hate to make people worry about me, so please don't worry anymore.
- Aria: ...I guess I darkened the mood a little, ehehe...
- Nino: No no, it's fine! I was the one who asked, it's not your fault.
- Aria: Well, let's try and change the subject!
- Aria: Do you have anything else you want to ask about?
So basically undertale.
with the prince as Asgore/or as we have seen from Aria's family dying Asgore but evil.
Homestucktale?!!
"magic isnt real" sis the Powers
tl;dr: Hoo boy, thats a lot of exposition to condense.
Aria explains there wasn't always a barrier and that humans and monsters could live and interact freely throughout the worlds, but racism was still a thing. Nino briefly insults Aria's tea before she continues. She explains she never fit in and had a bit of a loneliness issue before the war broke out, which ended with the creation of the barrier, which Nino very much does know about. Nino asks if they used magic, and Aria calls him a baka ("dummy" in Japanese) because magic doesn't exist. He then asks who started it, which Aria admits to not knowing, but assumes it was a lot of things.
The monster kingdom was basically ruined after the war, and the king got murked in it, so they were leaderless until the new prince showed up to rebuild it all. He then swore that monster-kind would never be hurt by humans again... and ensured this by genociding all humans in the monster world, including Aria's family, while she survived due to her disguise ability. Nino offers his condolences, and then gets tripped up in shipping fuel. Aria says it's totally fine, because she now has him and Five and Tori. She then asks if there's anything else she can explain.