Ok so I copy and pasted a template but made some tweaks of my own ideas. It'll either apply for the two of them, or each of them separated.
I'll be answering them in my own way, so I hope I don't anger the people who write reader inserts with these.
Enjoy!
A = Affection (How do they show affection?)
I'm not sure if you're aware of this by now, but they'll say they hate each other and beat each other up (mostly Kara doing the beating up) then they'll kiss immediately after.
Instead of saying something like, "I tolerate your existence," they say "I hate you."
Instead of saying, "I kinda like you," they say, "I hate you with every part of my being."
You get the gist. They're not sure how it started, but they love it for some strange reason.
B = (Best friend, who's their best friend out of the relationship)
Rex is close to all of his brothers, but has to admit that with Cody he feels a special connection. The way their generals act is a real bonding mechanism.
Kara doesn't really have any friends after she switched sides. Fives or Echo would probably be the ones she's closest to, just because they're always around. She also enjoys Ahsoka's company.
C = Cuddles (Do they like to cuddle?)
When they can find the time to be on their own, Kara likes to drag Rex to bed, and he'll grumble about how he has things to do, but he doesn't really protest.
He likes seeing the look of glee of her face as he gives in and lets her pull him down to cuddle.
D = Domestic (Do they want to settle down?)
In the middle of a war, it's not like Rex can just retire and go live in the country. Kara doesn't really want to give up her life of ACTION and ADVENTURE to go water a garden by some cottage, so she's fine to stay with him in battle.
But if they settled down somewhere, years after the war, Rex can see himself and Kara in a place together where he can wake up every morning and see her face. It's not like he thinks about how peaceful a place near a river on Naboo would be. He definitely doesn't dream about making her muffins to surprise her with when she sleeps in-
Nope.
He hasn't given it any thought.
E = Ending (Will they break up soon?)
Hopefully not lol.
Kara and Rex aren't thinking of ending things anytime soon, but we all know that things happen...
F = Fiance(e) (How do they feel about commitment? How quick would they want to get married?)
Kara doesn't particularly want to get married. Nope. It's just not something she's interested in. Rex was okay with it since he never really wanted to get married since he never thought he'd find someone in the war to marry.
G = Gentle (How gentle are they with each other)
Kara actually hurts him less than she has with previous partners. She just thinks his face is cute and doesn't want to change that. Not that she'd leave him if he got injured, she just doesn't want to be responsible for it.
Rex is soft with her. He has to be firm all day as a captain, and he likes being able to just relax with her.
H = Honest (How honest can they get with each other?)
Rex likes to think that they aren't hiding any secrets from each other. He hasn't told her everything in his life, but that's just because it's boring.
Kara is hiding things that she just doesn't think he needs to know. Like how she's struggling with the idea that she killed clones before. He definitely doesn't need to know that she thinks she's falling in love with him.
I = I love you (How fast do they say the L-word?)
We all know they take things slow. It took them like three months to finally admit they liked each other, then another month for them to ask each other out. It will definitely be a while until they say they live each other.
J = Jealousy (How jealous do they get? What do they do when they're jealous?)
They're both attractive, there's no doubt about it, so they each have people that find them attractive as a result.
Kara, if she were ever to get jealous, might sneak up behind and grab Rex's ass, glaring at whoever dared flirt with him when she was RIGHT THERE.
Rex on the other hand wouldn't do anything. He might scowl at them, but he knows Kara wouldn't cheat because of that one story she told him of the cheater and the knife, which he has tried to block out of his memory.
K = Kisses (Where are their favourite places to kiss?)
Rex is a sucker for forehead kisses. He thinks it's sweet and romantic and NOTHING can change his mind.
Except if Kara tells him she doesn't like it.
Because this man is all about consent and about what his partner likes.
Kara doesn't care where she kisses, just that it happens. She could kiss him on the cheek, forehead, or lips and it just doesn't matter to her.
L = Little ones (How are they around children?)
This is quite the question. Kara, is freaked out by them, as evident by the last chapter. They scare her, to put it bluntly. It's just something about their sticky hands that she just can't place...
Rex, on the other hand, loves them. There were so many cadets on Kamino, obviously the ones in training you see walking around, but there's also the infants and the littler kids. Rex thinks they're the cutest and would always stop by the nursery to visit with his vods.
If they were to have children (no promises on that, I haven't decided yet) Kara would take some warming up to the idea and would be very scared of accidentally hurting them. Rex would be there to comfort her and would absolutely adore the kid(s).
M = Mornings (How do mornings usually go?)
Kara is not a morning person, and Rex is well aware of that. He made the mistake of waking her up for breakfast once and will never do it again.
One word: Uppercut.
N = Nights (How do nights usually go?)
Kara tries everything in her power to convince him to stay up later with her to spar or just to talk, but he insists on a rigid schedule and WILL NOT stray from it.
So she grumbles and whines as he gets ready for bed before huffing and tucking herself in for the night. She rolls her eyes at such an early night, but falls asleep without much fuss.
And he smirks, successful in getting her to have enough sleep. She never catches on, and he does it every night.
O = Open (How open are they about their relationship in public?)
There's obviously no way they can keep it a secret in the GAR *cough* Fives *cough* so even if they try to hide it they can't really keep it a secret for long.
That said, they don't exactly make out in public. They think it's a private thing and that no one wants to see Kara stick her tongue down Rex's throat.
They're not big fans of PDA so all they do is forehead kisses (Rex loves them) or just quick kisses that barely happen.
P = Patience (What do they do that irritates the other?)
Kara does a lot to mess with him. She likes the way he glares at her when she steals his helmet, and when he gives her one warning before chasing after her.
Rex doesn't do much to irk Kara. Well, not much on purpose. He's planning to call her "pretty girl" just to give her a taste of her own medicine.
Maybe.
Q = Question (Do they trust the other fully or always think things over before jumping into things?)
Kara trusts him enough to go through with an idea in the heat of battle, and that's more than she's trusted anyone in the past. She's never trusted anyone enough not to always feel on edge, so this is a big step for her.
Rex trusts her, but is always aware of how things could go south. And no, he will not give an example.
R = Remember (How good are they at remembering the little things?)
Kara remembers the certain things, like his favourite flavoured ration packet, but doesn't remember other things, such as the training they were going to do.
He remembers that she forgets those things so he puts time into his schedule to go pick her up to take her with him to the training room.
S = Security (How protective are they?)
Rex is protective enough to force her head down behind cover in the middle of battle, but at the same time he doesn't not let her go. He protects her in the moment but doesn't take things too far. He's not overbearing or overprotective.
Kara once kicked someone between the legs for bumping into Rex, but in her defence he had hit on her earlier with a sleazy line so she was looking for an excuse to hurt him. She sometimes takes things too far, so he always has to keep an eye on her.
T = Try (How much effort would they put into dates, anniversaries, gifts, everyday tasks?)
Rex tries to make it as romantic as possible without seeming like he went totally over the top. He wants to make it special for him.
Kara doesn't see anniversaries as a big deal and at best would spend the day with him, maybe cuddle a lot.
U = Unique (What unique things do they do together?)
Training. They like to train together.
It's fun and is enough exercise for Rex not to feel guilty about blowing off his usual exercises to spend time with her.
Sometimes they have little contests and tie in the end, and it can get very competitive.
V = Visit (Would they visit the other in jail?)
Rex would absolutely visit her and push the limits of visiting hours, pulling rank so the guards would let him.
And let's be honest, if Rex got arrested, Kara would be arrested just so they could have the experience together.
Then his name would be cleared because he was framed and she'd be stuck in prison.
W = Whole (Would they feel incomplete without each other?)
Depends. They can be away from each other, they're not exactly one of those couples who cries when they can't see each other for a day, but if one of them were to die.. (which totally wouldn't happen 😅)
Then they would feel sad and incomplete.
X = Xtra (A random idea for them.)
Kara is obsessed with trying to grab his ass and he secretly wants to surprise her by getting revenge.
She knows that, based on the look in his eyes every time she does it, and wants him to try. When he does it, she's going to laugh at his pitiful attempt, grab his properly, then run away before he can catch her.
Y = Yuck (What are some things they don't like about each other?)
Rex doesn't like it when she calls him "pretty boy" at all. He detests it. He wants to strangle her every time she does it.
Kara hates how he pretends he doesn't like it.
Z = Zzz (How do they sleep together?)
Not like that, but nice try.
Kara hogs the bed and will steal all of his blankets. Rex will try to tug them back but will always be unsuccessful. Kara may be short and not as buff as him (which she's always complaining about) but for some reason she's scarily good at holding onto the blankets.
He's kept tally of how many times she's kept it away from him.
Kara: 23
Rex: 0
One time he got it back, but then she pushed him out of the bunk, so he doesn't count it.