B'Elanna, Neelix, Tuvok and Chakotay needed to star in an episode where they just talked about their different beliefs and approaches to spirituality/religion. Paired off and all together. I need to gain more insight. I need characterization and I need it to be messy.

okay so i’ve seen voyager all the way through once like a few years ago and i am currently rewatching it, plus i’ve been in the fandom sort of for like a couple of months, but like, i’m not sure i follow why b’elanna would be so extremely upset abt c7? i know there were some unresolved feelings(??) in the earlier seasons, and like sure, she might find it weird or that it doesn’t make sense, but why would she be like Super Upset and Resentful at Chakotay for it? is it something i forgot from the later seasons or am i just a bit dense LMAO 😭😭

You aren't dense and I don't think you've forgotten anything, as always when it comes to hypothetical scenarios I'm just laying out my opinion and my interpretation of each character, and it's totally fine if you see things differently.

I think there's also a misunderstanding here, in that I don't actually think B'Elanna would be 'super upset and resentful' about it, I just believe that she'd be disappointed in Chakotay's choices and wouldn't want to talk to him for a while because of this. I understand why this happened as I've made jokes about it for the most part and so I exaggerated things a bit, and that's on me. I don't think B'Elanna is the type to be resentful for petty reasons at all, and if I were to write this in a more structured narrative I would take a different approach in showing the situation.

My reasoning is mainly based on the fact that B'Elanna in canon doesn't really like Seven, and has also the kind of rapport with Chakotay where B'Elanna assumes (or hopes) he is on 'her side', but it's not always the case. I keep thinking about this dialogue between them in “Extreme Risk”:

TORRES: This whole thing is so ridiculous. I don't report a few scrapes and suddenly Janeway thinks there's something wrong with me. Typical Starfleet, huh? CHAKOTAY: You have been running holodeck programmes without safety protocols.

B'Elanna is referencing their shared history in order to make him stop questioning her decisions, but he isn't buying it. In this case Chakotay was justified in ignoring the attempt (she was injuring herself), but there are so many similar cases over the course of the show in which Chakotay explicitly does not take her side even when she's not in the wrong (like about her supposed 'anger issues' in “Juggernaut”). Additionally, Chakotay was the one who ordered B'Elanna to work with Seven when B'Elanna didn't want to way back in “Day of Honor”, completely overriding B'Elanna's authority, and I can imagine B'Elanna having sort of internalized the fact that Chakotay won't be on 'her side' whenever Seven is involved, which hurts all the more given the mentor/mentee undertones they've had ever since their Maquis days. A relationship between Seven and Chakotay would be the ultimate confirmation of her gut feelings, and while I don't think of B'Elanna as a resentful person, she does see the world as an 'us vs them' kind of deal. From her perspective, I think, it would feel like Chakotay is 'betraying' their friendship by forming a relationship with a person with whom B'Elanna's had so much difficulty getting along. She would be deeply disappointed in Chakotay for not understanding, but of course it's not like she's ever said anything to him about the way she sees their friendship.

It's obviously not a very "mature" response but honestly, I think it's very... human to have mixed feelings about a friend dating someone you can't stand (and that they know you can't stand) have had such a difficult time with in the past, and you still don't necessarily want to interact with very often (ETA: see discussion in the replies). And it's just as likely B'Elanna would never even mention that it's a problem for her unless someone prods her, although I do think she'd at least land a couple of sarcastic remarks about it, which may or may not feel like unwarranted attacks to Chakotay, hence the disagreements. But again, ymmv.

Tuvok & Seven friendship is so important to me. autism 2 autism communication

I love them so much...I want them to be genuine pals. I want Seven to find Tuvok after he gets literally assimilated fully by the borg and for them to actually talk about that after some resistance ("I'm fine. I do not require your assistance") <- An inverse of Tuvok pushing Seven to talk after 'Tsunkatse'. I wonder about loneliness and the borg and vulcan bonds and why Tuvok was the one out of him Janeway & B'Elanna who was assimilated. I want to know about the recovery process following that. I want it to become another thing they can understand about one another like the long silences and the eyebrow raising about silly Human things and the isolation. The Borg are a terrible destructive force but when you're within it it's ALL, it's like nothing else. I want them to spend so many evenings in silence together. With Tuvok, Seven doesn't have to think about 'Being Human' and maybe Tuvok can relax with Seven too - "Commander Tuvok & I" that kinship, stated resolutely. "Commander Tuvok & I don't require..." I want them to not talk to each other for years after Voyager and then Seven just appears where Tuvok is and he's like "Oh, this is unexpected. I am pleased to see you." and they're able to fall back into their old pleasant silences and go on walks together and maybe they go for a hike on another planet and while they're camping out they talk more about stuff they wouldn't if they were anywhere more familiar and at night maybe they talk about stuff they wouldn't if it were day. I want them to talk about their time on Voyager and how it's affected them and is still affecting them and for them to poke fun at silly Human things (some of which Seven understands more now like being in love and having fun and looking at a sunset) I want Seven to talk about how much Starfleet has hurt her and Janeway has hurt her even though she wasn't trying to and how she doesn't know exactly how to feel about her time on Voyager. It was the start of her life, the best years and the most confusing and the most horrific and stifling and freeing and [and and and] Tuvok talks about how lonely it was in the stilted way he does - half describing a flower and he'll never denounce the captain the same way the captain will never denounce Starfleet, the closest he'll ever get is that it was a difficult time - that he doesn't agree with every decision but he isn't Human, he can't say for sure what was right or wrong and Seven has to accept that that's all he'll do (it's difficult, she wants to push him but she knows it's useless) and I want them to find that they still can relax around each other despite it all - that they're different but that's at least the same. "Commander Tuvok & I"