#weebs asks

The first thing that came to my mind was @wynsnerdyrambles wonderful character analysis that Tanjiro's empathy for demons was, in a way, a coping mechanism. To shorten it, he has to believe that there's something more to demons. Something good. Because if he doesn't, then what is he fighting for? In canon, it's just a given that he would empathize with demons because of Nezuko. With her, he had a perspective from both sides, but without, there really isn't a reason for him to think that way. The only demons he encounters are ones that are blatantly cruel. (Excluding Tamayo and Yushiro)

I think he just wouldn't be able to find it in himself to sympathize with the sadness or fear they feel when dying. The hand demon laughs about how many of Urokodaki's apprentices it's killed, but is upset at it's own death. Kyogai trapped people in his maze-like house to kill and eat but cries when he's killed, feeling unappreciated in the time he was alive. On top of killing humans, Rui mistreats his own family but grieves when Giyuu finally decapitates him. There's a pattern there that Tanjiro picks up, but instead of being able to empathize with them, I think he would misinterpret their grief for their past life as self-pitying. And it.... infuriates him. All he's ever seen is the pain they've caused to himself and others, so his view of them is that they're creatures who feel entitled to take lives then act sorry for themselves afterwards.

Also on the topic of Rui, even without Nezuko, I think their fight would be very, very personal to Tanjiro. Witnessing the way Rui mistreats his family when Tanjiro has lost everyone.... oh boy. Oh boy. I think that would be the final straw for any and all of his composure, even if Giyuu was the one to deal the finishing blow to Rui, I think Tanjiro would end up in a screaming fit like he did after Akaza ran away. We'd probably get alot of those, actually! He's not here to make demons feel forgiven in their last moments anymore, he wants to make sure they know they aren't forgiven. He going to make sure they don't forget all of the pain amd suffering they caused. Tanjiro will be hand-delivering every demon he kills to hell himself if he has to. <3

But like I said, his anger and compassion can co-exist. He would still be very kind to other people, though more short-tempered and less tolerant of asshole behavior.

Zenitsu is still mostly the same (If not at a higher risk of being headbutted for disrespecting women. Tanjiro's momma raised him right, dammit.)

Inosuke too. Tanjiro's a bit less patient now though, so honestly they might clash a bit more but nothing serious.

I think this version of Tanjiro has mixed feelings about Giyuu. Tanjiro doesn't blame him for his family's death, but there's just some uneasiness between them because Giyuu blames himself. Obviously Tanjiro doesn't know this yet, but it's because they have such similar backgrounds. Giyuu can't help but see himself in Tanjiro and it hurts to think that there was a possibility he could have saved his family so their interactions end up being sort of stiff.

Overall I don't know if that many of his relationships would change for the worst, but I do think he would manage to make new ones!

This Tanjiro and Shinobu are very similar in their anger. Because of this, they probably get along terrifying well and whether it's good or bad, learning from her definitely nurtures his anger. I don't think she would ever purposely encourage it, as it's not a trait she likes in herself, but Tanjiro would be especially impressionable when it comes to her. He's around her alot, they get along well and deep down, he probably yearns for a motherly/sister figure, so it's only natural that he might imitate her.

And I think by extension he should also get along with Aoi. He's lacking without Nezuko, he needs more girlbosses in his life.

But basically: