I ask because I've become pretty curious about this topic. When you made your way through Mt. Silver and found Red there - what did you think? How did you feel about finding the player character from the previous generation there, starting a battle with you without saying a word?
See, when I first played Gold and got to Red... I found the entire thing really unsettling. I'd explored the Kanto region and found it kind of unexpectedly stripped down and depressing now three years after the story of the previous games - Cinnabar Island gone, the grass in Viridian Forest gone, the Pokémon Tower demolished and thousands of graves desecrated to make room for a radio tower. And the culmination of that general feeling of wrongness was reaching the deepest part of Mt. Silver and seeing what had ultimately become of me, the player character.
He'd disappeared into a dark cave, and now I'd found him there, and he was just... standing perfectly still, staring at an empty wall. Every other 'important' trainer in the game, the ones you have to talk to to battle them, faces downwards so you look at their face as you approach them; by contrast, Red was turned around, blankly ignoring me. And when I talked to him - he just turned around, gave me a "..." and then threw the most powerful Pokémon team in the game at me. After beating him, more frozen "..." - and then he just vanished into thin air before the credits rolled.
To me, this was a strange nightmare horror twist - sometime, in the space between these two games, Red had disappeared and become this creepy, mute, unresponsive hermit staring unseeingly at a blank wall in the deepest depths of a cave, who can't speak but whirls around to wordlessly, mercilessly wipe you out when you try to prod him, and then silently vanishes as if he were never there. My takeaway was that Red was possessed, or undead, or had otherwise somehow been corrupted into this strange, empty, uncommunicative husk. Creepypasta wasn't a thing yet back then, but as far as I was concerned, this whole thing was about as unsettling as when people started writing up stories of strange hacked cartridges where familiar characters have blank eyes with blood coming out of them.
Fan depictions of Red, and the more fleshed-out canon depictions that have appeared in recent years, though, never seem to be building on the creepiness that I found in all this as a kid. Instead, people mostly seem to interpret Red as just a regular person who is normally mute or barely speaks for innocuous reasons - either in an autistic sort of way, or in a he has such a strong bond with his Pokémon that he doesn't need to speak to command them sort of way. This has always been a little funny to me: the player character in R/B/Y explicitly isn't mute; we just don't normally see his dialogue, only the dialogue of the character he's speaking to (this is most obvious when speaking to Copycat, who explicitly repeats the words Red just said to her). But instead of seeing his silence in G/S/C as strange and unsettling, as I did, the fandom and eventually even the canon itself generally seem to have just folded it into his character in general, and reinterpreted the whole encounter as something perfectly normal and innocuous - just a normal case of finding a super powerful trainer somewhere and challenging him to a perfectly normal battle for who's the best. It probably makes the canon overall more palatable and in line with Pokémon's broad intended vibes, but it's always felt like kind of a shame to me, because the creepiness of the Red encounter was what made it really memorable to me.
So, how did you feel about Red, if you played G/S/C back in the day? Did the encounter also read as creepy or sinister to you, or did you figure this seemed normal and innocuous for the kid you played as in R/B/Y? How do you feel about the increasingly canonically implied interpretation of Red as being mute or mostly mute for innocuous reasons?