
"I hope this isn't going the sis-con route!!" It clearly isn't. The author knew that it would be a concern in this genre, so they put the whole "I want Diana to marry someone who makes her happy." scene in there. He's affectionate and easily excited, but he never treats her possessively and even scolds his father for objectifying her. The reason why people misunderstand him in the story is, that no one but him knows that Diana's life is in dangers. He even treats Al as a sad little kid, and not as a rival in love. It doesn't get clearer than "If they were to fall in love and marry, I'd have nothing against it.", he doesn't want to marry his sister, he wants his sister to not get murdered.
Anyway this is really interesting, and I think one of the better "reincarnated into a loving family" stories. The characters aren't reduced to ideal Arents who provide unconditional love and affection to their children, but they aren't cruel or abusive either. They have flaws that lots of parents have (comparing children, scolding children for something they encouraged, using children to appease superiors), but they still love them dearly. I understand why they're concerned about their relationship, because they just don't have the same info as we do. I like that Cain's idea of nobility, while good, is clearly false. His parents somewhat scorn commoners and free expression, but they're not the ones who are wrong about what nobles are like, Cain is, yet it's his ideas that make Diana a kinder lady.
In a way, it's a bit more mature look at nobility, than all those shoujo manhwas, where commoners are only there to virtue signal that the FL is a good person, while she continues to muck around with the emperor, forgetting about them as soon as they're out of frame.
I especially liked the cake eating scene. In other stories, the scene would be used to illustrate how loving the father is to his daughter, but here he's depicted as wasteful.
On a final note, if there's going to be romance, I think it'll be with the original FL, because so far she seems really nice, and I think Cain wants to talk to someone about video games lol.

He's still being a creep though. Even if he doesn't want to marry Diana, doesn't wanting to marry a woman who doesn't love Diana as much as he loves her and understand and accept that Diana is more important than her in their marriage is basically saying he is obsessed with her and want someone who won't get in the way. He might as well just Diana herself at this point. The parents are right (for once). I would also be concerned if my children would be acting like that and want to separate them

little spoiler
I kinda skimmed through the novel a little bit and it's really slow, there isn't much in term of romance for now. And I don't think the og FL is Cain love interest but you are right, she is nice ( and a bit silly ). She'll become one of their friends but she misanderstand and thinks Diana is the one reincarnated like her, if I remember correctly.
But yeah as far as romance go, Cain has some "moments" with Ilvareno, I guess... could just be baiting though.
Fun fact: Diana's dream about being a knight is gonna be one of Cain main objectives. Like he's gonna think about how to go about making it legal and acceptable for the public opinion and stuff ( girl knights exist but it is very rare and they are commoner not noble ).

Could a novel reader let me know why Callisto's heart meter went up so slowly? It's clear that he cared about her for a long time, so I thought there'd be a plot twist about his meter measuring something else, but that doesn't seem to be the case. Thank you!

Unfortunately I don't remember that ever being elaborated in the novel.
My personal theory, though, is that he is a very guarded person who is slow to trust. He was clearly interested in her but it took him a while to realize his own feelings, which is why I think his meter was only at 70% when he first proposed.
But that's just my interpretation, we'll never really know... ╮( ̄▽ ̄)╭

so my guess based on what ive read, is that his meter was the only one representing real romantic love. the others all had either familial or some kind of twisted "love" meter or whatnot, and he's the only one who genuinely started to fall in love with her. so in the novel when she asked him later about that time when she asked if he loved her at the party, and his meter was only at like 80 something, he was already in love but didnt understand his feelings because they're both ppl who didnt really believe in love.

Contains spoilers.
it's been a while since i finished the novel but, uh theres a couple points to this;
1. I remember eclipse's meter and callisto's affected each other when there was sudden spikes. so when pen got too close too eclipse, that made calli jealous with his meter going down.
2. as rantpanda said, all the other characters have twisted affection. in this sense, all of the charas's affection are correlated to Pen's past / game setting. Pinkie bro's is guilt for stealing yvonne's necklace and framing pen. Derrick's guilt for losing yvvone in the festival as a kid. The duke's guilt for overlooking pinkie's action, and trying to compensate her monetraily, and covering up her bad rep, than thru affection. eclipse - affection nurtured into possessive obsession.
None of these qualitfy as "love" vs callisto who is the only who has romantic affection and the closest thing to love for her.
also i think the 100 on the affection meter doesn't satisfy till the love interest either names, or acknowledges it as "love"
3. Both penelope and callisto supressing their emotions. pen doesn't have time or ease to leisurely take her time and enjoy life with calli in a situationship. She cant rely on an affection that would go away. That wont get her out of duke's house, or help her survive, or fulfill the system's conditions. That's why she made it clear to calli she needs someone who "loves her" to get her out of the system's hell (he'll find out about the system later too).
i dont remember if calli mentioned this in the manhwa, but basically he didnt want the royal family to control pen and take away her freedom and choice. Given his past with his family, he doesnt feel like he has the capability of "loving" normally, is my take on it, which he lowkey got over, after seeing pen in a comahere.

Haha, at this point it isn't even a reverse harem story, but a romance between Penelope and Callisto, while these other guys fumble the best girl so bad.
Which is not to say that I don't see Reynold being good, but he's not actually all that there for Penelope. Yes, if someone's being awful to her, he'll help, but it needs to happen in front of him. He's not someone who thinks things through enough, to plan ahead to help Penelope to get out of situation, just someone there for the confrontations.
And even if he was, I do think that their relationship is platonic/familial, and nothing more, unlike Derrick, who wants to have his cake and stab it in the back too.
Winters is really interesting, because he's kinder better person than Callisto imo. Winters is just not capable of living for Penelope, he has to care about the kids, his people, the kingdom and just justice in general. He'll say the truth even if it harms Penelope, which I do really admire in his character, but it just isn't something that Penelope needs.
In a story about Penelope dying if no one comes to love her, rational normal kind and honest man just isn't going to do it. Penelope needs someone just crazy enough to choose her over the rest of her world, but not someone batshit enough to disregard her happiness in this.

I actually love this so much, mc just went and seduced both of the spouses. They both know that mc means trouble, but they love her anyway. Fucked up, amazing. My previous comment was Rip to toxic Yuri, but actually, rip to toxic polycule, you could've been terrible together.

In a previous chapter it was revealed that they met before, and the mc was presenting as a woman at the time, and the dude fell in love with her. The reason he was so angry with mc at the start, was because he thought the mc was a brother of a woman he fell in love with, and that he did something to her.

I mean I wish yaoi on him as much as anyone, but it does seem unlikely. No matter how good a ship gets, this is a comedy manga where the chapters don't link together too closely, so I don't think it would switch to romance, as it would undermine the character and the story structure. But maybe the author will be able to write a romantic interest that is as absurd as the mc, so the vibe of the story won't change? If that's the case, I do think that so far the psychic is the best option, as he doesn't really like the mc yet, and thinks this whole bl thing is absurd.
Kind of shallow, convoluted and nonsensical, but in a fun way. It feels like the sort of story girls reincarnate into in better stories. It's fun for like five chapters and then it just stop being amusing in it's shallowness. The heroine is kind, The crown prince is stupid, The Lady is malicious, The sister is silly, The prince is an ideal person and there's just nothing else to them. The politics of this gave me a laugh "The crown prince is the one who's engaged to the duke's daughter and for some reason one brother knows about it and the other one doesn't!" Great fun