Tanjiro:

This wholesome boi absolutely loves hanging out with you. He's alright with whatever you wanna do. You wanna sit around and read? Sure. You wanna go to a nearby festival? He's so down.

He's probably one of the easiest ones to hang around because he's so agreeable. And the few times he suggests doing something, you can't help but agree. Nobody can say no to that face. Not even Giyuu.

If you two decide to be lazy and sit around, he usually likes to sit at a respectable distance from you. Reading? He'll chat amicably with you about the kind of books you like. Watching the others sparring? You two will eventually start laughing at silly stories about Zenitsu and Inosuke's shenanigans.

If you do find yourself doing something with the squad, he makes sure that you're having a good time. Every so often he'll ask you "Is this okay?" and "Are you having fun?" He's just so sweet that you really don't mind... even if Zenitsu's flirting with Nezuko gets a little grating. He does his best to rein in Zenitsu's and Inosuke's behavior, although if he really needs help you're quick to intimidate them into behaving (well, more like intimidate Zenitsu... Inosuke gets placated by giving him something greasy with a smile).

Nezuko:

Since she doesn't really speak, she usually makes happy noises when you suggest something she likes. If she really wants to do something, she'll tug gently on your hand until you follow her, though you don't mind.

She's a lot like Tanjiro in that she's down for pretty much anything you want. She's just happy around you (plus it gives her a break from the boys for a while).

If you two end up being lazy, she likes to sit close to you. If you're reading, she'll peek over at the book, reading along with you. If you're watching the boys sparring, she'll usually busy herself with something, like weaving flowers together or playing with your hair (as long as you don't mind... you never mind).

If you both end up doing something fun like going to a nearby village to check it out, she'll stay close to you, holding your hand gently. She always makes sure to be careful with her nails so that she doesn't hurt you. If you end up window-shopping, she'll probably end up looking for something nice for you and her brother, but won't buy it unless you notice and hand her some money for it. She likes sitting in the shade with you and watching people going about their day.

Zenitsu:

This boy is a major sweetheart. A bit of a coward, but a sweetheart. You say you wanna do something? Be prepared to do it with him, because he's probably not gonna say no.

He's usually eager to do whatever you want. You wanna sit outside and relax? You bet he's gonna sit right next to you. You wanna do some light sparring? He's a little nervous about hurting you, but he's down! You wanna go search out a hot spring or something? Oh-ho, he's definitely down.

He's a bit of a pervert still, but he's reined it in since you two became friends. He understands that it makes you uncomfortable sometimes, so he usually keeps his tendencies at a minimum (although you may need to remind him that you aren't going to let him peep into the women's baths if you end up at a hot spring).

He's just so happy to have a friend, you find it hard to be too mad at him. Usually if he does suggest something, he's pretty shy about it, and it makes you melt.

Inosuke:

Fitting with his piggy theme, he can be a bit stubborn. Actually, no, this is Inosuke. He's very stubborn.

If you do wanna do something, you may have to preface it with calling him 'Inosuke-sama' or something to that nature for him to agree to it. He may be disinterested with something peaceful, but if it involves being active (and chaotic) he'll most likely agree.

He's usually pretty rowdy, so bringing him to a village isn't much of a good idea... unless you're having an eating contest. If your idea of fun is running or sparring in the forest, he'd go for it -- just be wary of him getting too riled up and giving you a few bruises if he wins. He doesn't have anything against hitting girls, so he definitely won't pull his punches if you end up fighting. If you win, he'll probably sulk about it for a while, but he'll demand a rematch eventually; just make sure you're not in a crowded area when he does declare it.

If you can get him to do something more calm, he'll probably be a little fidgety depending on what it is. If you take him out stargazing, he'll be amazed at your knowledge and demand you teach him about the constellations.

If you teach him how to do something, get ready to be impressed at how quickly he can pick it up -- his years of living alone in the forest have made him very adaptable and a quick learner of hands-on activities. Teach him how to weave flower crowns for the fun of it; you'll get a very good kick out of throwing his flower crowns at Tanjiro and declaring himself supreme.

Giyuu:

Giyuu is a pretty collected person, but if you really want to do something, he'll probably say yes just because he'd like to spend time with you. He's a fairly lonely guy, so having an excuse to be a little more extroverted will be welcome for him.

If you end up sitting together, he won't really speak as much as you. You'll have to lead the conversation, but he is a great listener and can give some good input when necessary. If you read together, you'll get to sit in a comfortable silence with your books.

If you do something more extra, like going to visit another village for a festival or pulling a Tanjiro and asking to do an eating contest, he might be a little hesitant at first, but he would probably go along with it. If you look closely, you might even see him smile.

Kyojuro:

This tall beacon of sunshine, when not busy, would be down for just about anything. Especially if you get to eat some tasty food.

He knows a lot of great places to go for entertainment, so usually you'd ask him what he recommends, and you'll go from there. Sometimes you two will go to a nearby village that has some great fishing spots, or you'll find a waterfall so that you can cool off.

Other times you both can sit and meditate, feeling the peaceful atmosphere, or you can watch the other pillars sparring, or he can give you tips and can help you in your training. Since you've proven to be adept at (breath style), he believes you'll become a pillar someday.

Muichiro:

Muichiro is quite spacey, even now. But if you ask to do something, since you're his friend, he will probably say yes.

Simple things like sitting outside and watching the birds, or looking up at the clouds, is all good. You could even sit in a library and read up on your favorite books. If you need some relaxation, you may hit up a hot spring and meet up afterwards for some tea and light snacks.

Just as long as you're hanging out, he doesn't mind your company. If you end up hanging out with Tanjiro too, the three of you have a lot of fun sitting somewhere and chatting about what you've been up to.

Shinobu:

Since she's often busy, you usually ask if you can help her in her lab. She doesn't mind your help, as you've picked up some knowledge on some more rare poisons here and there from your time as a slayer. If she doesn't need your help, she may ask you to help her clean up around the lab.

If you do end up doing something, it's probably hanging around the Butterfly Estate. Sometimes you'll play with the girls, or you'll do each other's hair -- complete with butterfly clips. Shinobu is, unsurprisingly, very talented with hair.

If you want to do something more active, you may try sparring. Shinobu is very graceful with her fighting style, and you two usually end up appearing to dance together, much to the delight of your onlookers. If you need tips, she's got you covered.

If you just want to hang out and do nothing, she may agree to just sit with you and chat over tea. Usually you end up talking about the many shenanigans that the girls get up to, or you may talk about the other pillars (and conspiring to get Giyuu to loosen up a little).

Gyomei:

He's often busy, but sometimes he doesn't mind hanging out with you.

Usually you both end up doing something like cooking a meal or playing with the many cats around your house. You find it amazing how gentle and loving he is with them, and they seem to trust him just as much. He doesn't mind meditating with you, either. Just being with him is enough for you.

Other times, you may just sit and talk. You love hearing about his life and his religion. Oftentimes he'll be petting one of the cats in his lap as he speaks. Sometimes his soft voice lulls you to sleep, and if he wakes you up he doesn't seem to mind it, no matter how much you apologize.

Sanemi:

This guy is busy most of the time kicking names and taking ass, but in the off chance that he's free, he may come to you and demand to do something.

Sometimes you'll find yourselves engaged in a contest of some sort, like going through the forest seeing how many targets you can take down, or seeing how much anmitsu you can eat before you get a brain freeze (you always win, always). He's pretty rough in action, but you can see that he cares.

Sometimes you'll find yourselves sitting on a roof, looking up at the sky. In the rare moments that he opens up about his life, he tells you about his family, and his younger brother Genya. It always surprises you just how soft he gets when he talks about him, but when he sees him in public, he's standoffish and rude. He's just a giant, scarred teddy bear, and it makes you feel even closer to him than before.