Loki: hey can we barrow 2500$?
Mobius: what do you need 2500$ for?
Loki: Sylvie and I are stuck in an escape room
Mobius: what kind of escape room cost 2500$
Loki: jail
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Loki: hey can we barrow 2500$?
Mobius: what do you need 2500$ for?
Loki: Sylvie and I are stuck in an escape room
Mobius: what kind of escape room cost 2500$
Loki: jail
I think a lot of the division in the Loki fandom where Sylvie and Loki are concerned stems from the fact that despite the variants being central to the story, the show has avoided any definitive, unpacked truth about exactly what they are to each other and remained pretty ambiguous. And so the viewers are left to try to fit that concept to the closest-fitting framework they have. (And I don't think that's an oversight; I think it's a hundred percent intentional, but I'll come back to that.) There's a bit of a struggle to conceptualize something we don't have a reference for.
For some viewers, the relationship of siblings is the closest fit. And to an extent, that makes sense. If all the Lokis started out the same, if they were all fathered by Laufey, if they all had Thor as an adoptive brother, that framework serves as a pretty good fit. But it's not the same Laufey -- or is it? What then is the Laufeys' connection to each other?
For some viewers, the variants are complete strangers who happen to share certain aspects of their histories. This framework too makes sense to an extent, when we consider that the first variant pair we're introduced to and spend significant time with is Loki and Sylvie, who are deliberately portrayed as wildly different. But just as with the sibling framework, this one isn't a perfect fit, either. They are, on some very vital level, the same. The Lokis all say us/we. Sylvie tells Loki he can perform enchantment magic because they're the same. Even the core message of learning to love yourself quite literally doesn't work if there is not a degree of sameness between variants.
So okay. There is a core sameness.. But they're also in separate bodies and have unique experiences and memories. So we try clones as a framework for the variant relationship. But just like the other frameworks, this one fits in some places and not in others. Whatever it is variants share, it isn't perfectly duplicated genes.
So with none of those frameworks entirely working to spell out what the variants are to each other, we're left to try and puzzle it out for ourselves. And this is where I'll circle back to my belief that this is completely how the showrunners want us to feel. I think we are supposed to be confused and not sure what to feel because Loki and Sylvie are confused. They're figuring out what they are to each other, as well. They know they have a vital connection, but exactly what that is is unclear. And while there are aspects of their process of figuring this out that look like a romance, (here comes the magic word again,)that framework ALSO isn't a perfect fit. Hence the line "I don't even know what it is we're doing." And their difficulty pinning down a good definition of love. Everything about them defies strict definition and pinning down, and there's no reason their relationship to each other would conform to any existing framework: sibling, clone, romance, or otherwise.
Just my take on it. Do with it what you will.