In a pub just off the edge of canon, Mitsuri Kanroji was drowning her sorrows in food. This bar was untouched by time or space, simply existing in limbo until it was needed. And boy did Mitsuri need this.
In her Manga, she was exploring the Infinity Fortress, faced with wave after wave of demons, and tensions were high. Her master had sacrificed himself, and it looked like they were in the endgame. The Upper Demon Moons were gone, and all that was left was to take down Muzan Kibutsuji. So it was understandable for Mitsuri to want to destress. After all, she had faced uncomparable trauma earlier!
That demon boy called her stupid!
Mitsuri knew she wasn't the sharpest thumbtack in the board that you stick thumbtacks in, but he was just too rude! Plus she was sensitive about it! She was already self-conscious after that Pillar Meeting where she couldn't properly explain how she got the mark to appear, but then everyone kept looking at her with pitying glances and danced around the issue. She knew that the other Pillars probably thought she was stupid too, but at least they had the decency to not say it to her face!
All her friends had betrayed her, so now she could only turn to her meal. The savory, sometimes spicy, delights of noodles had never betrayed her. To fill the emptiness she felt in her heart, Mitsuri filled her stomach instead. But no matter how much she ate, it wasn't enough. And she ate a lot. There was a pile of empty bowls as tall as a 5'5'' tree on the tables.
Meanwhile, at the bar of the pub, Giyuu Tomioka was drowning his own sorrows in Non-Alcoholic Beverages. His words were slurred, his head was buzzing, and the Asian Flush turned made his face as red as a pink grapefruit. But he wasn't drunk, even if it was only for the sake of the rating!
Giyuu may act like he doesn't care what people think, but he does, and he is just really bad at expressing it. For instance, if you asked him how his day was, he may think that you are just being polite and greeting him. And since you obviously wouldn't want to talk with someone like him, he wouldn't respond. That was how considerate Giyuu was! Although from the outside, it may look like he was ignoring you.
And being the kind and caring person that he was, Giyuu wanted to know more about other people's thoughts and feelings. Specifically what they thought about him. But Giyuu also didn't want to seem desperate, so he could never muster up the courage to directly ask anyone what they thought of him.
So when Kocho told him that he was disliked, he was devastated. She took it back after seeing his reaction, but it stuck with him like gum on his shoe, which no matter how hard he tried to rub it off, he could still feel traces of it. And I mean, if he wanted to, he could have peeled it off at first, but that's kinda gross so he just tried to rub it off on the ground. But then that made it even harder to get off, since now it was spread around, and was being pushed deeper into his shoe too. So now he can't peel it off anymore with there being a ton of leftover gum still on his shoe. And apparently, you can get it off if you stick the shoe in ice, but there is no ice nearby. So you have to either walk around with no shoes until you get the ice, or you have to constantly feel the gum on your shoe stick and unstick from the ground whenever you take a step.
So that was why he was drinking (Non-Alcoholic Beverages) to dull the pain of being unpopular. Also the Infinity Fortress. That was stressing him out too, probably.
"All right, you'vs 'ad enough!" The bartender with a fake New Jersey Accent told Giyuu, "I'm cuttin' you off!"
"Youu cann't do tthat!" Giyuu slurred his rebuttal, "I'mm not drunkk!"
"Well, I ain't servin' you no more!" The Bartender grabbed Giyuu's discarded bottles of
DASANI® Water, Purified & Enhanced with Minerals, and threw them in the trash. "Oi! You're from the same manga, right?" The Bartender asked Mitsuri, who gave a nod in affirmation with a mouth full of noodles, "Take this guy back when you're done!" The bartender left him with her, even though Giyuu never paid him but his part in the plot had ended so what could he do?
So that was how Mitsuri Kanroji and Giyuu Tomioka ended up at the same table in a pub, despite only interacting once in canon. But boy, did Mitsuri feel awkward. They were like Geese who flew in the same V-shape, but whenever they hung out with their migration group, they would always talk to different geese. So whenever it was just the two of them, it felt awkward since they hadn't really talked before, but they weren't really strangers either. Also, one goose was drunk in this scenario.
"So, Tomioka…" Mitsuri attempted after the silence had long crossed into awkward territory, "That was a lot of DASANI® Purified Water you drank there, are you okay?"
"It just tastes so affordable, fresh, clean, and healthy! And it's available at your nearest grocery or convenience store," Tomioka defended, no longer slurring since it is super annoying to write that, but just imagine that he is still (not) drunk. But he eventually had to answer her question, "It's just…" Tomioka gave a wistful sigh as he reminisced about Kocho telling him that no one liked him almost 100 chapters ago, "Do you think I am hated?"
"What? No way! You're super cool! Everyone likes you! And I'm sure the other demon slayers and civilians are grateful for all you've done!" Mitsuri told him with 100% unfounded confidence. Mitsuri was a kind and empathetic person, so the idea of hating someone who hadn't done anything mean to her was just too foreign of a concept. Besides, even if he didn't talk much to her, she liked Giyuu. He was so cool the way he acted like a lone wolf. Sure, Iguro and Shinazugawa may have short tempers around him, but Mitsuri was sure they didn't hate him! She is the love pillar, so she loved everyone and wanted everyone to love themselves and each other!
"Do you really mean that?" Giyuu asked. Had he been sober, Giyuu would have never revealed his insecurity, but Mitsuri's earnest answer emboldened him. It was like being complimented on something you didn't hadn't put much thought into, but all of a sudden you feel proud of it and want to show it off. But years of being emotionally constipated made it hard for him not to second guess basic kindness.
"Of course!" Mitsuri assured him, which made Giyuu's dead expression soften a little. Seeing him vulnerable and soft made the distant Giyuu feel less distant to Mitsuri. Like when you realize that the objects in the mirror are actually closer than they appear. "Actually, can I ask you a question too?"
"Okay," Giyuu accepted despite being surprised. He didn't think anyone would want his opinion or advice because he had a severe inferiority complex.
"Do you and the other Pillars think I'm a moron?" Mitsuri asked him, mirroring his own question.
"No." Giyuu responded without even needing to think about it, "You need to have good judgment and be very skilled to become a Pillar. And mastered a sword that would be impossible for most, and you created your own breath too." He listed off all her impressive feats that he had observed. Giyuu may not understand the subtleties of human relations or even basic politeness, but he could respect their efforts. And there was also the fact that he considered himself to be less than his colleagues, which was probably the biggest factor for him doling out praise like that.
Although he couldn't say what the other Pillars thought about her, for obvious reasons.
"Yeah! You're right!" Mitsuri stood up from her seat, pumping her fists, "I am not stupid!"
"And I am not disliked," Giyuu also rose, because her enthusiasm was contagious. They locked eyes and nodded in unison. They clasped hands like those two muscular guys in that meme, and pulled the other a bro hug.
They had found a comrade in one another.