I don't get the "secret third thing" accusations
I think the statement "nor romantic nor platonic but a secret third thing" is kind of an oxymoron in many contexts, but especially in the context of shipping, and it definitely doesn't make any sense when it comes to sydcarmy.
One, cause that "secret third thing" would still be, by definition, still platonic.
The 'secret third thing,' to me, is just an attempt to put a name to elements mostly associated with romance: soulmatism, devotion, and a perpetual need/desire to be in each other's company. Even if those things can exist outside romantic feelings, in the case of Syd and Carmy, they have to be associated with romantic feelings, cause they do have romantic feelings for one another, despite what the narrative ever intended for those feelings.
So when all the "is a secret third thing" defenders come trought, what they are saying is that THEY SEE THE SOULMATISM, the things that cannot be fully explained by platonic love. They act like it's so noble to defend platonic love, but the truth is, most of the time, these defenders want the relationship to be categorized as definitely not romantic; they'd prefer this soulmatism to be totally devoid of any sexual/romantic possibility between the two people or characters. It is not different from this: "they were such good friends," used to describe queer closeted people in a relationship. This is a statement that is based on the idea that it would be 'better, more appropriate, more pure, more conventional, more noble' if these two particular people weren't involved in a sexual/romantic relationship. It is rooted in prejudice and social norms. (Cause God knows there are a lot of videogame 'fans' that sexualize characters that look like children, but that gets less hate than the interracial couple).
Back to the 'platonic' accusations.
Everything in Carmys and Syd's relationship: their artistic partnership, their friendship, their rivalry, ALL of that existed (and was built on) in the context of them having romantic feelings for one another, again, regardless of what they wanted to do with those feelings. All they did for each other, the ways they tried, failed, and succeeded to get closer to one another and be there for each other. All of that had the potential for a romantic resolution, built on a bridge of romantic desire (that was, most of the time, being actively repressed, yet it managed to surface every fucking time).
This point of "there should be space for platonic soulmates" is particularly obtuse to me when it's applied to sydcarmy. Cause
It is established that none of them has a romantic relationship that rivals this soulmate-like devotion. The show even went so far (by accident or intention) as to have Syd handle more of Carmen's struggles, doing so in such a selfless way that it was almost like they were telling us she was the better match for him and his recovery.
Both of them have expressed physical attraction and romantic feelings for each other. With Sydney, it's even in the text, in the things she says, in her themes on the show, and in the actions she takes. That was part of her character arc, even if you were to believe she was supposed to get over those feelings. For Carmen, it was most evident in his physical behavior around her and in the way he remained reminiscent of her in everything he did and considered her his ultimate safe zone.
Even if you believed that this feelings were always meant to be supressed, if you were blind or biased enough to not see Carmen feelings for Syd, or if you ignored Sydneys character in such an obtuse way so you believe her affection for him was always supposed to be one sided, this love triangle did leave a space for a romantic possibility between sydcarmy, cause that's what happens when you write a love triangle. The secret third thing is just a way to try to shame people that wanted them together, because we dare to believe Sydney was a better match for Carmen.
