a friend of mine told me that aspect roleplay doesn't exist, and when i tried to bring up the fact that OD basically said that Xefros is acting like a Knight of Time but is very clearly a Rage player, they just brushed it off because it's only Act 1, and talking about time all the time doesn't make him a Time player... but that's the kind of stuff that Homestuck does, right? how can i explain that to them? and are there other aspect roleplay things that i can use to help explain it?

I’m not exactly the best one to ask I’d say, I like the theory but OD does know way more about it than I do. That being said though, call it Roleplay or call it whatever you want, but it is a mechanic that’s confirmed in-canon.

UU: player abilities may also manifest in ways in defiance with their aspects if they are heavily resistant to their trUe calling. or, if corrUpted in some way by an oUtside inflUence.

We can see this in its most blatant form with Rose- Where she goes off the deep end to the point she goes Grimdark and becomes very Voidy. It’s not just her Aspect that changes though! Her attitude as well, and her way of using her powers, transcend Knowing and Guiding and focus on an extremely aggressive and active, spell-using, Aspect manipulation and alteration powers. She’s still driven by knowledge and the search for it before going Grimdark, but after, she’s outright going to fight Noir. Hell she even uses Consorts as Familiars, and is constantly said to be really Witchy. 

However it doesn’t have to be corruption. Rose does mention, after all, how her drinking Alcohol was a way to connect with her mother- Taking a Symbol of Void and muddling her Light for it. This same take of a Symbol of someone is extremely obvious with Vriska! Except her Aspect matches that of her Ancestor… So her obsession with Mindfang can only manifest with her Class. And we really do see it. She takes on the imagery of the Fairy that’s associated with Sylphs. She’s constantly Making shit happen, trying to ‘Improve and Fix’ Tavros. Much like Rose’s search of Knowledge, ultimately a lot of what Vriska does comes down to Stealing the Spotlight, but you can see those behavioural quips coming from her admiring Mindfang and looking up to her.

The thing about saying “Talking a lot about Time doesn’t mean you’re Time”, is that. That’s not true? Constantly relating yourself to an Aspect- One which also makes sense due to societal expectations of the Timebound Rust Caste? That can’t just mean nothing, not to say it goes beyond him talking about Time, it’s in the Arena Stickball imagery, it’s in his constant Lack of Time to do the things he wants, in his slow-moving Lusus that makes him waste Time, not reaching Joey in Time and just waiting to bleed out or burn to death- His entire existence is being oppressed by Time honestly. Which is why we thought he was Time, because his themes with Time are EXTREMELY heavy. We’re not saying ‘Xefros roleplays the Time Aspect’ because we want to save our old theories- We say it because we’ve seen an OBVIOUS, blatant connection with Time, but we’ve been told he’s Rage, so there must be a reason why he’d be so connected with Time. And his Aspect? Yeah, being Forced into Service, just like Jane was forced to be Condy’s Heiress, just like Rose suppressed her true calling due to her more Active upbringing and her anger, leading her to act like a Witch.

The Truth Is Out There.