KarlNotFound is pretty unknown in the mcyt community in general I’d say, so I'm here to help spread the agenda as much as I can.
I have some songs in mind for the pair, mainly Kingston by Faye Webster, Bubblegum by Clario, Dreaming of You by Selena, and Once More to See You by Mitski. Also I know people love to debate about whether the feral boys are catboys or dogboys but I’d personally say George is a catboy/bunnyboy with dogoy tendencies and Karl is a dogboy with catboy tendencies. They’re both just so full with energy and it really shows when there around each other.
In my opinion the pair has sort of have a “winter” vibe that can be implemented in sort of meet cute or pining aus, maybe with some fantasy in the mix? Both seem to love putting on specific outfits, normally oversized clothes (mainly George) and both are considered small, though Karl is more lanky and George is just plain short. They’re perfect for clothes swaps, they themselves said they’d switch hoodies when they meet up and Karl even mentioned sniffing Georges sweater when they did. I feel like Karl would be the type to share his clothes with George and George would happily comply, loving the way bigger clothes look and feel on him. Honestly because they don't interact much one on one on streams or videos its hard to get a complete read on how thy treat each other and their overall dynamic, BUT Karl sure does feeding knfers when he can. I think their relationship is really based on warmth and comedy and once in a while being genuine. They're a giggly duo most definitely, Karl always being one of the main people who can get a giggle or laugh out of George, just by his voice alone! They both seem to love being comedic, so the fact that they're almost ALWAYS giggling when their with each other is extremely important. There's never a dull moment when they're around each other because they know how to appeal to each other, such as George playfully flirting with Karl once in a while just like Karl will do (though a lot of the times he’s being genuine and just expressing his admiration with George which always seems to put a smile on Georges face) or Karl making a dumb dnf joke to get a rise out of him and their audience. They get each other, is what I'm essentially trying to say. They're very dependent on having fun, or just talking about their own interests and having the other listen adoringly and just genuine expressions of admirations or jokes. Their laughs just.. compliment each other so well. They’re also pretty jokingly mean to people, they're the type to poke fun of you and roast you in a lighthearted away and will act the same towards each other, but you can always tell its not serious when they erupt into giggles and repeat themselves. Their humor can be so stupid but it works. And lets not forget all of their silly inside jokes.
Now I haven't even mentioned both of their love languages, Karl's definitely being physical affection and verbal affection while Georges is quality time and also physical affection (shown by Tommy's vlog). Karl already shows his verbal affection towards George every once in a while, whether its in the guise of an inappropriate joke or its him being genuine and telling him how amazing he is (reference to the cooking stream where Karl had at least 2 instances of hitting on George) and it never fails to make George smile or laugh. Karl knows what George likes and isn't afraid to express himself and make the latter happy. Karl also is extremely affectionate physically and just touchy, whether its leaning on someone, punching or pushing them, hugging and grabbing their arm, its as if he cant get enough. Now compare this to George, someone (as shown in Tommy's vlog) doesn't complain when he’s given affection and actually with reciprocate it and enjoy it or easily comply. Now we got to see Karl make Sapnap warm up to physical affection but what about when Karl jumps on George for a hug and George doesn't complain, just hugs back and smiles, always having fun if Karl’s around. Additionally, George is a person, while he might not always express his love for his friends, he is one to show it. He’s been reported tp spend hours on vc with Sapnap and has been shown to be on the phone with Karl multiple times, as well as talking to Dream daily and being shown on tons of his friends streams and constantly talking to them. So put Karl and George together and you get people constantly spending time with each other, probably cuddling if they met up and showing how they care for each other in their own silly ways. They truly bring out the best in each other.
I’ll leave you with an AU I thought of a while back:
KNF are in a stereotypical fantasy world, where Karl is a prince locked away in a tower guarded by a dragon (Dream) and George is a wandering traveler and mercenary looking for work and one day he comes across Karl’s tower and out of curiosity and the need for a place to stay he finds his way in and finds a sleeping dragon. He sneaks past and makes his way up to the top of the tower and finds Karl who calls for Dream and he tries to bargain his way out if the situation, only to discover that Karl is lonely in his tower and he’d actually like George to stay with him because though he’s lonely, he likes it where he is. George agrees as long as he’s able to go out once in a while. From then on they live together and love blossoms.