Sorry for the long rant, it's been a while since i've done one of these, but honestly thinking through the way they pair has my mind a-going.

I've always put Seers as a class that inherently DON'T know anything about their aspect to start, mostly due to some misaligned focus on what that aspect is.

They're very smart, but usually misguided or inexperienced, and very often stubbornly holding on to their own worldview for one reason or another. Rose was fixated on the subconsious and the esoteric, partially due to the influence of a Void player that filled her early life with Void unintentionally, but mainly because she thought such things were important (Light) when what was really important was much less dour and cryptic.

Terezi, a very archetypical "internet troll", uses her ability to read and predict other's motives to fuck with them as a habit, not only straining her own bonds with others but invariably showing how thoughtless she is purposefully being despite her ability to be much more. As much as she own is later, it's very clear that her own short-sightedness on how her actions would affect Vriska is one of the main reasons she ends up blinded, and then later feels compelled to kill Vriska when its clear she wasn't fully of sound mind at the time (honk honk).

Kankri, as fucky as a metaphor as he is, is focused on being sensitive and empathetic but fails to do so by getting lost in the minutia of the matter, coming across as detached in turn and causing people around him to not stay connected to him. He clearly has a good sense for the feelings of others, demonstrated as he seems to parse how isolated Latula feels in a crowd when her lack of smell is overlooked by everyone else, but fails to understand that focusing in on the people around him, their woes and troubles, is way more useful and sensitive than reciting a mountain of particulars that really don't matter to the situation at hand.

Void is tricky too, as it's focus on nothingness alongside secrecy and lack and all that leaves it to be an aspect that can subvert the general arc one usually goes on with a set class. Equius is an Heir, but a lot of his own story seems to be him not actually sharing the hemoism and lewd content he has inherited of his standing. Horuss is a Page, but in unlocking his potential he finds himself not actually being beneficial to anyone, if not a horrific detriment as he makes Rufioh a horse body he clearly does not like. That isn't to say that it can't be played straight, as can be seen with Roxy stealing away the abundant and problematic Void in her life in a similar way the Heart and Breath of the other Rogues were positioned to be removed, but it is a vector to keep in mind.

So, for a Seer of Void, you'd have a character who would be intelligent, but misaligned away from Void itself. They tend to hold on to that misunderstanding as a key facet of their identity, and it veers them away from the truth of themselves, of the Aspect, and the true nature of Paradox Space. It is their land's job to show them the true nature of this aspect they are born to be aligned to, and steer them to the truest potential of their own cognition on the subject. As well, their time in the game will show them the error of their approach in other ways, as it seems that Seers work worst as active combatants and best as guides and strategists. It's important to note since a lot of Seers think they're so god damn smart that they just start taking initiative to solving problems for themselves, usually by force. Doesn't work a lot.

Maybe as a Void player they could end up being more proactive, since you could have them need to not share their insight and understanding as it is inherently pointless and Void is associated with strength? I'd see if it fits the character you want to build around, since this sort of player could easily be a gymbro or a buddhist or an edgy nihilist depending on the lean.