OKAY WOW THANK YOU GUYS THIS MAKES ME SO HAPPY!!! But since I have way too many AUs, I'm going to keep these answer centered around canon. Otherwise this post would literally never end. Also, just to the anon who offered GinHiji and HijiGin, to me, those are the same thing. It's why you'll see me tag stuff as GinHijiGin because I literally could not care who tops or bottoms, I'll take them every which way under the sun! Thank you guys again, it means a lot =A=

who cooks normally?:

Gintoki, but it's mostly badly shaped rice balls. They don't have a 'normal' by any extent, but on the times they eat in, Gintoki is the master chef. He's the one that has the apartment with the kitchenette and if they're at the barracks looking for a meal it'd just be stuff from the kitchens that'd already be cooked for them. And if Hijikata cooks, Gintoki knows everything will be smothered in mayonnaise and he won't abide by that at all. 

how often do they fight?:

Every time they see each other over anything for any reason. Even one of them glancing at the other can result in fighting of both physical and non. And then there's the actual fighting where they've hurt each other in some way, intentionally or not, and it results in fantastic makeup sex. Though, hurting each other intentionally doesn't happen often at all, only when they're really pissed off and worked up over something. 

what do they do when they’re away from each other?:

Miss each other and pretend not to, especially Hijikata. Gintoki will hide the fact that he misses Hijikata, but sometimes it'll get so overwhelming that he'll go off and drink with someone like Hasegawa and spill all his woes in the form of, "That goddamn bastard! Don't need'em anyway!" Whereas with Hijikata, he'll forever deny that there's anything to miss. He'll throw himself into work and just keep working and doing anything he can to distract himself and he'll run himself into the goddamn ground until he breaks and has to do something about it. 

nicknames for each other?:

The usual -- natural perm, parfait freak, mayora, otaku prince, dumbass, moron, bastard, idiot, etc.

who is more likely to pay for dinner?:

HIJIKATA! Gintoki has infinite tricks and methods to leave Hijikata with the bill... or to give Hijikata enough incentive to want to pay the bill. As in Gintoki doing his damnedest turning Hijikata on in any way possible and make him want to pay for the food quickly so they can go find a spot for themselves. Like Gintoki wouldn't be shy in running a hand up Hijikata's thigh and touching himself in place he knows Hijikata likes to be touched and doing it in such a way that it's sensual and draws Hijikata's attention to it. 

who steals the covers at night?:

Hijikata. Every fucking night he's hoarding the covers and pressing as close as he can to Gintoki because he needs and likes the heat. Usually they can share okay, but Hijikata is such a glutton for heat that he'll fight for rights to the blankets -- though, his favorite heater is Gintoki, nothing keeps him as warm as pressing himself up against Gintoki's firm body. 

what would they get each other for gifts?:

They're not really into gift giving, but on rare occasions, the staples are always good. Dango and strawberries and parfait for Gintoki and for Hijikata a pack of cigarettes and mayonnaise are both good choices. Gintoki will surprise Hijikata with things if he wins at Pachinko, one of those random acts of thoughtfulness that take Hijikata by surprise every single time and make him blush up to the tips of his hair. They don't need to get each other anything, really, they're content just being together. 

who remembers things?:

Neither and both. Hijikata is the more organized one, but he can get so wrapped up in work that he can forget things, even important things without meaning to. Gintoki will remember things at random, but for the important stuff, he'll always know. He may appear to all the world like he forgot and act completely normal, but for something like Hijikata's birthday, he'd know and he'd do something for it in his own way. They never forget the important dates between them, but they also don't do anything really over the top. Making sure they spend time together on those days if they can is important, but they also understand that if they're busy then it just can't be helped because that do have their own lives to live. 

who cusses more?:

Hijikata. They both cuss a lot, but Hijikata with his shortened temper can let the profanities fly! It's not really even noticeably more or anything, he kind of just has more reasons to. Yamazaki not filling out paperwork properly, Gorilla Kondo dashing off naked to go court Otae, Sougo disappearing when he's supposed to be working, Gintoki following him around keeping him from his work -- the man has a lot to deal with! 

what would they do if the other one was hurt?:

It's situational. The more severe the injury, the harder it'll be for them to keep themselves together and composed and on task. Like Gintoki isn't the type for vengeance, but if someone hurt Hijikata, he'd be all over it. He'd throw himself into whatever situation no matter how dangerous, god, he'd do whatever he could to keep Hijikata safe. Neither of them will really think things through in more dire situations, they'll just react to their feelings, which isn't always the smartest thing. 

who kissed who first?:

NNNNNNNN -- Gintoki! Please see next question.

who made the first move?:

Gintoki! There's something between them, a pull that will get Gintoki following Hijikata around at first only to tease him and bother him, but then move onto something more. The teasing won't be teasing anymore, like it will, but there will be more to it, an underlying of something else. It'll be attractive to both of them even though Hijikata will act all annoyed and stuff. But Hijikata won't be the one to really push things along, that'll be Gintoki. He won't even be looking for a relationship, but that's what they'll both end up with. It'll be entirely physical and they won't even realize they've fallen in love until it's too fucking late and GUHHHHHHHHHH ETERNAL GINHIJIGIN FEELINGSSSSSS

who started the relationship?: