I’m kinda free-wheeling here, and answering this as though they got married ;)
Gary, at first, but he teaches Miranda how, and she begins to surprise him with her culinary adventures…
how often do they fight?:
Frequently, but they always make up in the end, and often fight just for the making up ;)
what do they do when they’re away from each other?:
They have their own friends and lives, and are not together 24/7, Stevie and Miranda keep a weekly date, and Gary goes out with Clive…
nicknames for each other?:
Miranda keeps her name, but Gary likes to tease her by calling her Mrs Preston, so she teases him back with Mr Hart (or whatever her last name is ;))
who is more likely to pay for dinner?:
Gary, and Miranda never objects.
who steals the covers at night?:
Miranda is the covers hog
what would they get each other for gifts?:
Miranda loves to surprise Gary with new and odd kitchen gadgets, which he immediately puts to use. Gary loves to surprise Miranda with flowers.
Miranda believes she has the better memory, but Gary has to help more often than not
Gary can cuss a blue streak, but tones it back over time
what would they do if the other one was hurt?:
Gary is very good at patching up Miranda, but when he gets hurt she falls apart and he ends up comforting her!
Good thing that’s canon! Gary!! But Miranda considers their first kiss to be the one in the restaurant when he first came back from Malaysia.
who made the first move?:
This has caused many fights in their relationship, and they’re content to fight about it forever more
who started the relationship?:
Miranda, imho, with her confession of love. That was what got the wheels turning for Gary.