I think that it's quiet interesting. But I'd like to add that getting interests from other people doesn't mean that it isn't the real you or that you don't truly like those things.
I'd explain with my own experience (it may not be as thoughtful as I'm at my job and ppl are being quiet 'pushy' today)
I am a neurodivergent person, and I think that Papyus is, too (ND monster, I mean) . When I was young I related a lot to him and I was over heels for my boi.
So, when I see these theories I tend to sometimes see some of myself in Papyrus, wich could psychologically explain my interest for him.
For example, right here with this post:
Papyrus seems to get his interests from others, right? Well, I do that, too. Sometimes is either for positive reinforcement or just wanting to fit in.
My favorite shows, games and hobbies have came from someone else, usually my older sister (ex. My sister likes art, I started to like art bc of her. My sister was playing UT and I decided to stuck with her and I loved the game. That and many other things)
Most of them were when I was younger, but now days I don't have another interest that differes from such.
I wanted to look cool to my sis, I wanted to spend time with my siblings, I wanted to make friends so I just followed and learnt about what they seem to do or like. If I don't I just don't get friends at all (most of my stronger friendships started bc we shared an interest, lol)
Also, when Papyrus gets asked what his fav food is, he doesn't know. I used to not know either(btw it's spaghetti, bc I liked Papyrus and he likes it and I like to eat it so i decided it was a great fit. Specially since it made me more Papyrus-y) , becuase I don't introspect at all, I'm "too busy" (Papyrus says he is too busy to even sleep)
So, I go through life based on goals (such as success, good grades in school in my case, being a Royal Guard for Papyrus) and spend my day focusing on my interests instead of self-care.
If people are perseptive they may know what you like even if you don't say so, based on what you're driven into and other stuff (Sans probably does that to get Papyrus' gifts, furniture, etc). It's like if others knew me better, others should tell what I like and what I don't. Perhaps it comes from the fear to be alone.
So, Papyrus wants to fit in, wants to look cool, doesn't know himself bc he rather go doing stuff than thinking stuff (this may come from insecurities, depression and other things. It's scary to look deep into oneself)
That may be the origin of what he is into, but it doesn't mean those things aren't truly of his like or special to him.
-He likes to cook spaghetti because every else loves it. So he wants to make others happy AND spend time with his BFF, Undyne (he prob thinks he'll mae more friends that way, too)
-He likes puzzles, that one seems from his own (or from the underground's norm. Being too rigid about norms is another thing we seem to share). And him saying that they're awful doesn't mean that he doesn't like them, he's being "objective" (yep, I do that, too. I don't like to be blinded by my preferences so I can tell it's pros and cons, admit if they are cringe and so on). If anything, it proves that he likes them so much that he doesn't care that they are awful.
-With his figures and race car, well, they were given to him by Sans, who IS very perseptive. Sans prob sees that he'd may be into those thing by hearing him talk, glance at things and o the stuff, he puts attention to Papyrus, and as Papyrus seems to really like the gifts (if Sans doesn't read to him the advanced puzzle or Fluffy bunny he'll get cranky, he dreams about having a car, he puts his figures on a table so they can be seen, they pretty much do a lot together, like Papyrus' battle body/costume, and so on)
He likes all those things genuinely, no matter if they came from someone else. He treasures something in those activities and stuff, and even seems to get into them deeper than others (omg, another thing we have in common. I get even more into things than the ppl I got them from)
Being influenced is not a bad thing, liking what gets you close to others shows that you cherish them and they moments you spent together.
Tho Papyus DOES have more to him than we know, I wouldn't call him a lier (according to certain theories), if anything he is insecure and ND, and if he is actually hiding some important plot stuff he must likely doesn't have a bad intention to do so or maybe would come out with something like "I didn't tell you because you didn't ask" (he is like me, fr)
Another thing is that ppl say that he lies a lot to Sans, but I don't think that's the case, it's just REALLY hard to know when they are joking or not.
Papyrus seems genuinely interested into those things, he just gets influenced by others and lacks introspection. Doesn't really need to straight out say what he likes bc it shows with behavior (you have to put attention to ppl like him to notice what he likes)
He may be hiding something (bc he really is smart and clever) but not with bad intentions/on purpose.
(If he turned out to be an actual lier I'd be broken)
Papyrus is so cool! Give him lots of love~ (without having to drag Sans down, pls)
P. D. Thanks for writing this bc I did some accidental introspective when I read this. It really helps to understand myself better.
And sorry if this is boring, messy, badly written and makes no sense. I am tired, at work, and wrote it with lots of interruptions and with no food in my stomach.
