These are all MC-specific.
A = Affection (How affectionate are they? How do they show affection?)
With friend: Coda doesn't mind physical affection, though they prefer it to be verbal. Fist bumps/low-fives/shoulder bumps are their bread preferred physical affection. They like performing acts of service and kindness.
With FWB: Literally all the same except more prone to casual physic affection. Wrapping an arm around your shoulders. Touching your elbow. Gently keeping you close/steering you if in a crowd.
With lover: Very fond of casual affection. They will touch you often and without much thought. They enjoy snuggling whenever you're afraid home together. They will often give you a shoulder and neckassage out of the blue.
B = Best friend (What would they be like as a best friend? How would the friendship start?)
Coda is already your best friend! You've been together for 15 years - through most of that time (other than college) you've been attached at the hip. You're more like two halves of the same whole.
It's not that you NEED to be together - it's that being together is inherently nicer than not. It isn't something you even think about - the two of you gravitate to one another.
C = Cuddles (Do they like to cuddle? How would they cuddle?)
Friends: Coda is fine to lean against you/have you lean against them. Or sit with legs tangled on the couch. Cuddling is a bit much -they like their personal space-, but they'll allownit if you initiate. The even find it comfortable once they get settled.
FWB: With always be down to cuddle. They'll be less prone to initiate it out of the blue, but they're the type of person who will undercut your argument or whining by drawing you in close and not letting you go until you feel better.
Lover: Loves it. Lives and breathes being close with you. It's always casual, always simple, but that's how Coda is. Quietly and gently there, your other half.
D = Domestic (Do they want to settle down? How are they at cooking and cleaning?)
Coda is already living a domestic life - they cook and clean regularly (and we'll!). Their favorite thing is hanging out with you on the couch and watch TV, listening to music, or playing video games. They like loving on an apartment so they don't have to do maintenance or lawn work, though. That stuff blows.
E = Ending (If they had to break up with their partner, how would they do it?)
At any relationship stage: Coda couldn't leave you. Not by choice. Not even if you changed completely. You're their other half - your souls are connected. youd have to be the one to leave, and you'd have to make it very clear it was over. That you never wanted to see them again. They'd be devastated - they'd never recover. But they'd honor your wishes.
F = Fiance(e) (How do they feel about commitment? How quickly would they want to get married?)
Coda isn't the type to get married on any stage of a relationship. They don't see the point of making your feelings and emotions the government's knowledge. That being said, you two are practically domestic partners already, so it's not like getting married would be a big deal if necessary.
G = Gentle (How gentle are they physically and emotionally?)
Very. To those who don't know them well, they seem a little aloof. Even a bit smug. But they are extremely intuitive when it comes to the needs of others. They are always watching and making adjustments to make sure things are as pleasant as possible. Their touches are solid but gentle.
H = Hugs (Do they like hugs? How often do they do it? What are their hugs like?)
Friends: hugs are cool. They don't give them out unless they think it's needed. They will usually accept if you offer to hug them.
FWB: same as above, but hugs are more lingering in this stage. Firmer.
Lovers: Their arm will be around you in a half-hug in public. They'll hug you from behind when they enter a room and you're preoccupied with something else. They'll draw you into their arms on the couch or bed. It's second nature.
I = I love you (How fast do they say the L-word?)
Friends: they have already told you this platonically. Many times.
FWB: They will stop saying it. If they need to, they will add "...as my best friend" to the end of the confession. They are very careful to keep the FWB from getting further. ...Until they can't.
Lovers: They will say it at the end and start of each day at minimum. They'll say it fondly when you do something silly. Honestly and warmly when you do something sweet. In a silent sort of awe when they randomly look at you and boggle at how you're theirs and they are yours.
J = Jealousy (How jealous do they get? What do they do when they’re jealous?)
Friends: Coda doesn't get jealous. You have your own life and they are glad to be a part of it. If you have someone else, that's cool.
FWB: Same as above. ...Until the feelings get too real, and then it's a bit messier.
Lovers: Coda wants you to themself, but they aren't one to pen you in. If you find another paramour, they will try to be supportive for as long as they can. They won't leave you, but their self-worth will suffer greatly.
K = Kisses (What are their kisses like? Where do they like to kiss you? Where do they want to be kissed?)
Coda's kisses are usually languid - attentive but slow, deep, all-consuming. If things are getting steamier, their kisses ramp up in pressure. They'll nip. They'll become insatiable, kissing you as if they need you to breathe.
Their favorite place to kiss you is the hallow of your throat and breastbone. Their favorite place to be kissed is their neck and shoulders.
L = Little ones (How are they around children?)
Coda is very good with kids because they're patient, attentive, and treat them as if they are autonomous. They let kids be silly and smart without trying to cage them.
That being said, Coda doesn't seem themself as being a parent. If you wanted kids, they'd conceed. Even if you can procreate, they'd prefer to adopt.
M = Morning (How are mornings spent with them?)
Friends: they get to sleep in for as long as they want. When they eventually get up and shower, they want a big breakfast. Then, ideally, a walk. Running errands is acceptable during this time.
FWB: Same as above except they'd love to either come into your room for morning sex or have you wake them up for the same. Then doze together before getting up to eat and do chores.
Lovers: Morning sex. More sleep. More sex. Doze. Shared shower (possibly with more sex). Make breakfast together. Go for a walk/run errands. Come home for - you guessed it. More sex.
N = Night (How are nights spent with them?)
A nice home cooked dinner, a little wine or your drink of choice, and movies/tv shows. Video games if you're both feeling up to it.
FWB or lover: add sex in there somewhere and they're a very happy person.
O = Open (When would they start revealing things about themselves? Do they say everything all at once or wait a while to reveal things slowly?)
You already know everything about them. Except why they have beef with Tove, but you'll eventually crack that case.
P = Patience (How easily angered are they?)
Very. They try not to let anything bother them too much - both of their parents had high blood pressure and a penchant for yelling, so they tried to go the opposite path. They see hardship as a blip of annoyance to work through and move on from
Q = Quizzes (How much do they remember about you? Do they remember every little detail you mention in passing, or forget everything?)
Coda remembers a lot about everything, but especially you. It's be crazy if they didn't, given how long you've been close.
R = Remember (What is their favorite moment in your relationship?)
When you drove overnight from your college to theirs to see their first big concerto performance. They saw you from the wings and knew they would do well because you were there for them.
S = Security (How protective are they? How would they protect you? How would they like to be protected?)
Coda will protect you with everything in themself. They know you would do the same for them.
T = Try (How much effort would they put into dates, anniversaries, gifts, everyday tasks?)
Coda is very 2015-era Pinterest Mom coded. They will put in so much effort to theme your celebrations.
For their special days? They just want to chill. If you plan something big, they'll do it, but their ideal day involves just hanging out with you.
Everyday things are met with attention and care, but the casual kind. They don't half ass things, but they aren't making a spectacle of it, either.
U = Ugly (What would be some bad habits of theirs?)
They chew nicotine gum - not to quit smoking, just in leui of smoking. They are definitely addicted to it.
V = Vanity (How concerned are they with their looks?)
Coda is not very vain, but they do take special precautions in caring for their skin. They have more skincare products than you and have a cycling schedule of routine maintenance. They also maintain their short fro and fade meticulously.
W = Whole (Would they feel incomplete without you?)
Yes. They're worried they won't survive without you in their life.
X = Xtra (A random headcanon for them.)
Not a headcanon, but lore. Coda went into medicine because of you.
Y = Yuck (What are some things they wouldn’t like, either in general or in a partner?)
They don't like when people ignore/talk around waiters/nurses/service staff like they aren't there. They don't like being treated like they're subservient/seeing others treated thet way. They will instantly lose all respect for that person.
Z = Zzz (What is a sleep habits of theirs?)
If they are sleeping alone, they have to have a pillow to snuggle. If they are sharing a bed with you, they almost always have their arm around you, a hand on your back/arm, etc. They like feeling you breathing beside them - it helps them sleep.