I really liked this story. I liked how Endrance was being nervous when Haseo came over. Also how Haseo was kinda beating him himself up what to do with his feelings. Anyway nice fanfic.

"And.. you too

[You have a habit of leaving twin periods instead of a complete ellipsis (…). That looks like you’re making punctuation mistakes, not leaving trailing segments. That or it's upload faults, but either way it's distracting]

except for bursting out the occasional "Ol Repth

[Odd, while Pi’s not a chatty party member, she’s much like Haseo in being forthright…even to the point of being brusque. If she’s seeing something uncharacteristic, she’s more likely to straightforwardly say “you’re acting strange. What’s going on?” than simply accept silence. She might not have the patience (or companionability, depending on your interpretation) to push if he is determined to be silent, but she’s not going to go silently]

Half of it is still left unsaid because it is all so stupid

[Foolish perhaps, yet so very much how we humans tend to act]

a sting of disappointment, like a punch to the stomach

[Those are rather…far from each other. A sudden realization that forces you to stop and reconsider your life is “like a punch to the stomach”. An annoying possibility would be…perhaps more “like a fly stuck in the room, buzzing around”]

probably go batshit having to wait

[I’ve heard the profanity as an emphatic, but you’re missing the “crazy” or some such state of being]

it doesn't matter what it is

[This is one of the problems I had with Endrance. His life revolved unhealthily around Mia. When Haseo pushed Mia out of the way and accidentally found himself the center of Endrance’s attention…NOTHING CHANGED. Endrance, for all his pithy aphorisms, never got ANY better even through Vol 2. He never grew up and realized that he needs to respect and live for himself at least a little or nobody else is going to be able to respect him either. Endrance is rather a void in terms of self-actualization and realization, and while this might make him a great Heartless in another game, it leaves him with one overbearing obstacle to his being an interesting person that might be able to interact with others. Without fixing that aspect of himself, he CAN’T have a real relationship with others]

Haseo thinks that's what he's saying. His own heart is beating too loud

[I still don’t think this fits. You haven’t established with consistent clarity that Haseo is wrapped up in Endrance’s opinion of him…at least, not to the degree that would call for this]

But Endrance is tall, and thin

[Well, Endrance is, though I find it amusing that despite the fact that the story’s BEEN in the real world for a while, all of the references were still as if they were PCs]

Haseo - Ryou now, he reminds himself

[I think he’s in need of a therapist if he’s referring to HIMSELF as his PC name instead of his given name]

which causes another fresh bout of blushing

[Why? All he did was sit down. I’m seeing no catalyst event for any embarrassment, and there’s no note of the two sitting awkwardly without being able to think of something to converse about]

and that he doesn't really need the money but wants something to do with his time

[A good character point]

"Atoli insisted on inviting Sakaki too

[That’s…possible. That poor girl remained stuck on him even after all of the nasty things he pulled in Vol 3]

He packs down his M2D in the laptop bag

[I note you never mentioned this when he was coming…just saying]

does but never dare

[Maintain your verb tense: dares]

it falls down to flail ineffectively at Kaoru's side

[“to flail” is most certainly not a calm or minor gesture. People’s limbs flail when they’re having a seizure, not when they’re physically withdrawing due to uncertainty]

While the technics are better written than the vast majority of fics on the site, I find some concern at the lack of transition. Canon leaves openings for all of the things you mention, most certainly, but you still have to build a bridge from that rather centrist point to the tangent destination your fic lies on. There are a few moments, yes, but canonically Haseo appears to tolerate Endrance, feeling more annoyance (and eventually a grudging acceptance/respect) than affection and while you convey the awkwardness of how the results might feel I don’t feel like there’s enough of a transition from the powerful compatriot to the object of continuing social interest.

I really liked this. You did a good job of showing Haseo's frustration and uncertainty, and the awkwardness of their meeting. I wasn't sure if there'd be a happy ending or not, and that made it all the better when there was.

Also, I have to say, I'm curious about why you chose that title.