Celestia and Discord are something else…. It's a common thing for them to view each other as the opposite genders and or switch them (with some Discord magic, but right now, they're being naturals). Hehe, Discord is Celestia's Baby Girl while Celestia is Discord's Baby Daddy… *sigh* it's illegal to have them in the same room… alone.

Honestly, I'd feel like Discord would be mom of the two (even though he's not the one who bore their offspring… Athena… he should've been). He would stay home and watch over his two little rascals (I mean, one of them isn't his, but still) and teach them how to be like him. Besides, he has the power to clone himself, so multitasking will be a BREEZE (maybe). And if he is feeling pooped or lazy, then he'll just simply go over to Fluttershy's and have her help him. She doesn't mind, but Big Mac… mhhmmm, maybe (he doesn't want his wacky magic around his daughter).
Now Celestia on the other hoof is more than likely out doing some type of business (idk what rn, probably travelling and or being a teacher still… just something social… heck, she'd probably own her own business!…. Idk, I'm still thinking 😅). Honestly, Celestia could be out up to no good as well (if you know what I mean😏😤…. Discord is used to it, but still not over her one night standing with his brother!! Yes, ons is a verb now! That's one thing he can't get over though.) Besides, she usually "dates" her besties, Queen Novo and Rain Shine….that's… really it (other than hitting on big strong stallions, like Rockhoof or even Bulk Biceps …..yeah…Celestia's hormones are everywhere!). Anyways, yes, these two, they're crazy, and meant for each other (though in history Celestia had to punish Discord's ss like a million times…. but as you see, he's somewhat redeemed now…right? Probably not, it's Discord).


⬇️Random Backstory Insert⬇️ (… idk, some relationship context)

As orderly as Celestia was when she was Queen of Equestria, deep down within her, she still had that chaotic side to her. Honestly, since she was younger, she's always wanted to have fun with Discord's chaotic magic (not in a world ending destructive way) and or, just simply have fun. But she really couldn't, because especially back then she was viewed as a more orderly, responsible and controlled pony, and not somepony who would tamper with stuff like that. Of course she can now, with this new freedom of not being a Queen anymore, and FINALLY be herself and not have to worry about imperfections and being a huge role model to anypony (she still likes to be flashy though).
Anyways, she felt more inclined to be with Discord because of his silliness and freedom of magic. She's always wanted to freely use her magic (especially after she turned into an alicorn) and experiment with it, but Starswirl kept her from doing it (to keep her from overexerting herself). She wanted to get lost into Discord's surreal realm he calls home that he always took her too in their down time. Even though she was doubtful of following him at first (because of Starswirl's warnings), she grew to feel comfortable around him… those were really the only times she could feel like herself again, free. Discord loved to see the joy in her eyes, the sparkle of life that she used to have when she was a wild and free filly. That's one of the main reasons why he always bothered her, because he knew, underneath that stern and demanding personality she had (the personality that Starswirl molded), was a carefree and joyous mare, waiting to be shown again.
However, though she truly felt bliss in those exciting moments, afterwards, she would regret it and get sadly upset at Discord for taking her to those worlds because she knew she couldn't stay in there with him eternally and hide from reality forever. She would always say, "You can't stay in a fantasy forever, because it's not real. You're gonna have to snap out of it sometime". For Celestia, being a princess was alright, but then becoming the Queen was extremely difficult of course. Having to be responsible for all of the lives in Equestria, and make sure that all of your people are safe was a burden alone unbearable to bear. It was a stressful task given unto her (and Luna and Callisto too, but she was the main leader) from Starswirl, and she barely managed. It pained her that the overwhelming responsibility of being a ruler would in turn ruin most of the relationships she had with all of her friends and family, especially in between her and Discord. Although Discord were allies with the others (North Star, Luna and Callisto), they still didn't trust him very well, from his chaotic magic and warnings addressed by Starswirl, but Celestia did (sort of). She was really the only one he would show his other dimension too and wacky tricks. But after a while of stress building up in Celestia, she sort of lashed out at him saying that he was a distraction and all, and that his magic wasn't going to do her no good but just make her more depressed.
Since Tia was the only pony who basically acknowledged his existence and magic and were potentially close friends with each other, he felt very heartbroken to hear that, but also very angry. Howbeit, he was not only mad at her though, he was also mad at the world for not accepting his deviant personality and magic and being grateful when they needed him. He almost felt How best, and used… And that wasn't fair, though he kept his promise to not wreak havoc amongst them. But now, he's had it, now he wanted to show Equestria what he 'is' truly capable of and let them wish that they shouldn't have doubted him…and thus started the reign of Discord, as he deemed himself as the Lord of Chaos (but we're not gonna get into that now… you already know what happens).

Admittedly, when Discord came back the first time, Celestia was scared out of her mind. She thought that he was out to basically…. Destroy her, because the guilt that was building up inside of her all these years were giving her intense anxiety (and that's what she thought he would do if he were to return… And did absolutely NOTHING to her… sOOoOo…. Well mainly also because the mane six whooped his ss before he could breathe, but that's besides the point).
Celestia, (after some friendship training), also let the mane six redeem him, (because she couldn't do it herself, for mental reasons). Having it be a test to observe their true friendship skill was an actual excuse to redeem him on Celestia's part (she knew that they could do it… though he's still a mess up… and is still Discord). So after his Bestest Friend Fluttershy (hehe BFF) got him cooled down, Celestia and him were finally able to talk things through. She said her apologies and so did he. After a while of chewing the fat, they were able to reunite their friendship and relationship, and continued what they were supposed to have when they were younger…. (They lived happily ever after… until Discord's brother came back!! But that's until next time….)