Since you are rewatching KHR, let's go with the old but good Bel/Mammon plus, of course, as always from me, Reylo! :)
When I saw your ask I felt that I’m coming home. What a nice feeling.
(it’s long so I pot it under ‘read more’. I offer condolences to mobile users who must scroll through my wall of text)
SEND ME A SHIP AND I’LL BREAK THEM DOWN
How did they they meet?: They probably met for the first time when Bel joined the Varia. Rewatching KHR reminded me about few things, for example that Akira Amano’s timeline doesn’t make much sense, but I assume Mammon joined the squad shortly before Bel. Considering that back then Bel was still a kid, he most likely felt better with another member who looked young.
Who developed romantic feelings first?: Bel, I guess? Mammon appears to be a person who shelters themselves from any feelings or emotions (or at least tries but often fails), so I don’t think they would reflect much on the romantic life. On the other hand, in Bel’s case “developing feelings” would be equal to immature games or something
Who is their biggest “shipper?”: I’m hesitating. Lussuria is a possible choice as he’s that Varia “mom” and searching for potential affairs seems to be something he would do. But I also want to mention Fon because the whole “conflict” with Mammon came from the fact that Fon considered Mammon to be too materialistic. I think he would be way too proud if he noticed Mammon thinking about something other than money and Mammon would be once again very annoyed
When did they have their first kiss and under what circumstances?: Obviously we need the “Akira Amano is not afraid of plot and actually lets the curse to be fully broken” AU. I can’t think about anything serious here… I imagine them playing together a video game (I still love that official art with them playing games) and out of boredom coming up with a bet saying that the loser must do whatever the winner asks for. Then Bel proposes a kiss because it’s funny, and Mammon agrees because for an assassin it’s still less humiliating than avoiding the lost bet?
Who confessed their feelings first?: Bel, but I don’t think it would be very serious either. Bel is so megalomaniac, he would most likely say that he really likes Mammon because with them the great prince is not bored and Mammon would just react with “fine, fine”, but pretty much ignored him?
What was their first official date?: Expensive. It’s pretty obvious that if Mammon agreed to go on a date, they would demand the most expensive entertainment. Nonetheless, I believe Bel would be rather OK with it. After all he’s a prince, he wouldn’t spend time like a beggar
How do they feel about double dates/group dates?: I doubt they have enough friends for double dates ;) Mammon for sure would hate that idea but Bel? Why not? In the end Mammon may agree because this way the date is cheaper. However, Lal and Colonello are the only pair that comes to my mind so I do not think the double date would be successful
What do they do in their down time?: Killing people. Playing games. Trying to survive while living with Xanxus and Squalo. Normal stuff.
What was the first meeting of parents as an official couple like?: Unfortunately, they don’t have parents so I can’t say jokes about mothers-in-law. Lussuria and Squalo are the only mom friends. So, Lussuria would be more than joyful and Squalo would come with all existing insults, adding that the world is ending.
What was their first fight over and how did they get past it?: They fight a lot in canon but it’s always about some stupid stuff and I don’t think it would change. They argue about everyday life and because both Bel and Mammon are objectively nerve-wracking people. But again, it’s never so bad that they need to make up.
Which one is more easily made jealous?: Mammon has that “I don’t care attitude”, I just must pick Bel. He would probably repeat that nobody can get what belongs to the prince and Mammon would again simply ignore his moods.
What is their favourite thing to get to eat?: Remembering how the Varia dinner looks like, I think eating anything is an achievement :) They look like people how like junk food. Bel is a lazy brat and being raised in the palace, he would consider snacks to be something new and fun, while Mammon eats it just because it’s cheap.
Who’s the cuddly one? What their favourite cuddling position?: Bel liked to, uhm, squeeze Mammon is the Arcobaleno form so I guess it would stay the same. What’s more, Bel comments that adult Mammon is really short so they have the proper height to be hugged in every form
Are they hand holders?: Probably yes, but only because Bel likes to show everyone that Mammon is with him and Mammon doesn’t care enough to stop him
How long do they wait before sleeping together for the first time? What’s the circumstances?: I’m sure it would take much time. Mammon looked like a child for too long to just ignore it
Who tops?: I guess they would be pretty equal
Who does the shopping and the cooking?: No one. Bel’s name comes from the devil of sloth and it’s enough for me to headcanon his as lazy. Mammon would think that servants are paid to take care of them
Which one is more organized and prone to tidiness?: Again, no one. But Bel looks like someone who lives in total chaos so Mammon is probably a little more organized than him (not that it’s hard)
Who proposes?: Mammon, explaining that if Bel wants to continue their relationship, he first should give Mammon his account access and half of fortune.
Do they have joined Bachelor/Bacheloette parties or separate?: I believe Mammon would totally hate the idea of a party but Lussuria doesn’t take no as an answer. So joined, because Varia organizes it
Who is the best man/maid of honour? Any other groomsmen or bridesmaids?: This is the moment when I realized that they don’t have any friends. Hmm… Bel would most likely say that he doesn’t need anyone and Mammon? Let’s just take the Arcobaleno as groomsmen and bridesmaids, even if Mammon doesn’t want to see them. Fran and Uni can be children with flowers :)
Big Ceremony or Small?: Big if Varia founds it, small if Mammon must pay even a little
Do they have a honeymoon? If so, where?: Japan, of course. The best mafia location
Do they have children? How many?: The realistic part of my soul tells me that no, they don’t, but nothing here is realistic and Varia would be better in rising children than they think so yes, at least one :)
2) Reylo
How did they they meet?: Of course we can stick to the canon material, but personally I like the theory with Rey being born in a Jedi family and meeting Ben when she was still a child
Who developed romantic feelings first?: I think Rey would be faster to show some kindness to Kylo Ren, accept his changes, but Kylo would probably develop romantic feelings first (and keep it secret for a long time)
Who is their biggest “shipper?”: Hmmmm…. unfortunately, I can’t think about anybody who would be supportive of their relationship. Rey’s friends could at most tolerate it but they would also remember that Kylo Ren was their enemy and Kylo’s allies are out of question. Maybe Chewbacca? Even if he’s angry at Ben, for sure he would like him to change
When did they have their first kiss and under what circumstances?: Dramatic scenarios don’t suit them, the couple is pretty dramatic anyway. I think they would kiss only when the war is over, if they took care of their personal matters, find peace etc. Then Kylo Ren can visit Rey again and love can bloom
Who confessed their feelings first?: Rey. As I said, Kylo Ren is an angsty kid and he would never admit that he has feelings for Rey. On the other side, Rey was living on her own for years and now she has problems with building relationships, so they would need time to fall for each other
What was their first official date?: Considering that Rey spent her childhood on a desert, I think Kylo Ren could take her to see some green places or to the sea. Yeah, she was training on an island but relaxing on a beach is not quite the same
How do they feel about double dates/group dates?: They would rather dislike it. I think both Rey and Kylo Ren would be very self-conscious when it comes to feelings and they would be simply ashamed of being more intimate if someone was watching them
What do they do in their down time?: Kylo Ren looks like a fun guy, I’m sure spending time with him is interesting. But honestly, Kylo Ren seems to be that person who doesn’t have free time because he’s always busy with plotting and being cunning. And Rey was working really hard, I doubt she had much time for herself. So I think together they would try different things to find something they like?
What was the first meeting of parents as an official couple like?: I… probably shouldn’t laugh so loud…. We don’t know anything about Rey’s family so who knows, maybe Kylo Ren will have a chance to meet them? So far Rey liked Kylo Ren’s parents, too bad that she won’t have a father-in-law
What was their first fight over and how did they get past it?: They had their first big fight long before they became a couple, I don’t think any quarrel can compare to their beginning. But I assume they would argue a lot, considering that they both have strong personalities and don’t like listening to others.
Which one is more easily made jealous?: Kylo Ren was introduced as a pretty… unstable… person, I guess he would be the jealous type. But I doubt Rey would let him behave immature, she would immediately scold him
What is their favourite thing to get to eat?: We know that Rey was forced to eat awful food so I headcanon her as a person who later loves eating and tries all possible tastes. Maybe fruits? A desert girl would surly love them and it would make Kylo Ren happy
Who’s the cuddly one? What their favourite cuddling position?: As much as Rey is distant with others, I believe she would be the cuddly one. She was lonely for too long, then she would seek company and physical contact
Are they hand holders?: Hmmm… yes, they are. After something as awful as the war, holding hands would seem like the most normal thing and they both would need it
How long do they wait before sleeping together for the first time? What’s the circumstances?: Long, because their relationship wouldn’t be easy and for sure Rey would need time before letting someone to be so close to her
Who tops?: Rey? I think Kylo Ren would be too angsty
Who does the shopping and the cooking?: I can’t imagine either Rey or Kylo cooking. Rey was starving, Kylo Ren had his subordinates. So I guess they would both do it because they both need to learn
Which one is more organized and prone to tidiness?: Kylo Ren, because he is the leader type and likes when everything is under his control
Who proposes?: Kylo Ren, although he would be pretty nervous and hesitate a lot
Do they have joined Bachelor/Bacheloette parties or separate?: I feel they wouldn’t like this kind of things. Kylo Ren is not the social guy, Rey has two close friends. They would probably find it unnecessary
Who is the best man/maid of honour? Any other groomsmen or bridesmaids?: Rey doesn’t have any close female friend so I think she would ask Finn. And Kylo Ren… maybe the best man is also a stupid idea, just like the bachelor party
Big Ceremony or Small?: Small, just friends
Do they have a honeymoon? If so, where?: On a calm planet where nobody knows them
Do they have children? How many?: Once I created for you a Reylo daughter, I’m gonna pick Luce again :)
