Theory: Kris and Yellow have OCD ON PURPOSE!!
Ok so I know Kris and Yellow having OCD are semi-popular headcanons (and very popular if you have OCD haha), but these aren't just projections. I am sure these allusions to the disorder itself have been put into the game on purpose.
We know Toby Fox has been aware of OCD and how it works (not just handwashing or "being tidy" stereotypes) since the Halloween hack days. Look at this screenshot:
(footage from "BRANDISH: The Most Obscure Inspiration of Toby Fox" by Daniel Movie Productions)
So this could be read as either "oh this dude will literally murder people if he leaves this is bad and edgy", in a similair vein to saying that Kris enjoying the sword route in any way means they're a bad person, but I don't think that's how it's meant to be read.
I think Toby Fox knows how OCD works and this little piece of dialogue means that this dude's OCD is making him believe he has to do a this ritual or he will actually kill people.
This is very much an unusually good understanding of OCD for a kid in the 00s. Toby explores a lot of psychological themes like that in the hack itself so I think it's something that he's interested in.
Now other people have compiled a lot of evidence on why Kris has OCD way better than me so I'll just copy the propaganda from an OCD poll from the person that convinced me on this:
"They canonically have hand washing, checking, and repeating compulsions, and do those enough that Toriel (their mother) doesn't question any odd behaviors of the Player. There's also a lot of dialogue implying they have intrusive thoughts in the weird route, and the amount of discomfort they feel about anyone implying they want this. With the coding in mind, the themes of control and autonomy with the PLAYER resonates with me so much… I will forever believe this is intentional until Toby himself says it isn't.
1. With their compulsions, I love how others respond to them. It's either just a thing they do, not a big deal, (others worry always made me feel worse), or if it's concerning people respond to it genuinely but lightheartedly, and never in a condescending or belittling way. The type of things people have learned to snap me out of spirals.
2. They have flavors I don't see talked about a lot, like "psychological harm" (semi-canon, included in discussed "obsessions") and "losing control of self" (interpretation of player's puppetting them). I don't know if there's specific terms for them because I haven't seen anyone talk about that specifically. Both are themes I've always had a hard time with and it feels lonely b/c I never see anything, so having a character with the same flavors as me means so much! Agghh I love them. (I also headcanon magical thinking and responsibility, which doesn't have much canon evidence but us a personal headcanon lol)
3. Also, did I mention the themes of control and autonomy in the game? OCD has always made me feel like I have limited agency and control over my life, and it's so hard to explain, and this exact nature always just. Made sense. They're literally being puppetted by the PLAYER, and in the every route they take out their fury at it on the SOUL (what we use to control them). While we can't hear Kris, others responses to what they do say and how they act on game options shows they're an entire person, and they hate this. In Dark Worlds (which take projections of Lightners when formed kind of? It's hard to explain) the implications this is some "secret want" is so… god. And they hate that. They hate that so much."
(via @/neonful-splodesauce on @characters-brackets)
When it comes to Yellow - he is one of the flowers who in some way are supposed to represent Asgore's family and even though Aqua seems more similair to Kris themselves I wouldn't think it's a stretch to see a connection between them and Yellow too.
Yellow's OCD- like tendencies have been noticed by the community way faster. He acts a lot like someone who has Moral OCD. He's obsessed with everyone doing the right thing, especially himself. He wants to punish people and spirals at the thought of himself doing something wrong and tries to self-harm.
It is very rare to see these kind of themes represented in fiction for a disorder that is known as a casual "wow I'm such a neat freak" (WRONGLY). I believe this is because Toby Fox is familiar with OCD and it's symptomps and put it there knowingly.
So I guess that's my addition to the OCD theories :)
