I have been tricked OTL I think I can agree that mine change depending on my mood or what fits with what I want to see in MRM at any given point lol, but let me try to name the most persistent ones:

-For Mob, definitely a praise kink. He's elated at seeing Reigen being proud of him, and would maybe be a little too serious in following his advice/instructions in bed lol. I also think he might have a thing for being ordered around a little hehe. Probably he could develop a thing for those sock suspenders and ties, from seeing Reigen wear them so often. Not sure if it counts as a kink, but Mob being so into seeing Reigen sucking him off... In any case, I think I have a much more difficult time thinking of Mob's kinks in particular, it really depends on the mood/au.

-For Reigen, he definitely has a degradation kink. How intense depends on my mood, but I feel like him trying so hard to give off an appearance of being a functioning adult in control of his own life might make him enjoy Mob being a little mean to him here and there. Also he 100% has an oral kink of some sort. He can't stop putting things into his mouth in canon, he so makes a whole feast out of sucking Mob off. Also ever since the omake where he chokes on a rock thing and people started drawing fanart of Mob sticking his fingers into his throat to lodge it out my brain chemistry was altered forever.

AH, also, for both of them: they have a kink related to pretending they're still shishou and deshi even once they're both older. I personally want Mob to have a kink of blowing Reigen under his desk while they pretend like they're still 2814-ish, so there's that too

To be perfectly honest, I'm completely indifferent towards it. Just going from the canon storyline, I can't see any chemistry between them whatsoever, other than "they're both adults" lmao. But it's not really that I dislike the idea of the ship, it just doesn't interests me.

HOWEVER, because of how the Western fandom behaves about them, I can admit I became a little resentful towards Serirei. Nowadays I always see artists' media tabs before following them to see if they post about the ship to try and check if they're an anti or not; 8 times out of 10, if they draw Serirei, they tend to be an anti.

However (x2), I sometimes like art of them made by the Eastern side of fandom, since it tends to be a little more neutral/canon-aligned than what I've seen the Western side of fandom portray them as. I suppose what I dislike about the latter is how most of the time antis actively change Serizawa and Reigen's personalities to make them fit their own narrative, so to me it's not even them, if that makes sense

I got into MP100 back in 2017, around March-April or so. I think I first heard of it from the Anime Awards debate that happened because Yuri!!! on Ice got the 'best animation' award and a lot of people started posting examples of MP100's animation as a protest etc. Once I watched S1 I fell in love with the series, but I didn't read the manga until late 2022.

I also never joined the fandom even though I was a fan lol. So I didn't really get a feel of how it was until 2022, once I finally joined it on twt while watching S3. My first impression was basically "sigh" haha. I'm glad I went to the MRM side, because seeing how full of discourse and petty drama the anti/Western fandom is, I wouldn't have wanted to stay (already have experience with those types of fandoms since 2013, no need for more tbh OTL)

I'm not sure if you're being literal about the sandwich or if it's meant in the horny way, so I'll answer both options.

Actual sandwich: it'd probably be one of those soft breads that have blueberries or some other type of berries inside, where at the first bite it's soft and unassuming on your tongue, until you bite one of the hidden berries and bam. Explosion of flavor (ofc the bread would be both Shigeo and Mob). Reigen would be a nice few slices of Serrano ham, lettuce, and maybe some gouda or Edam cheese. The condiments could include either french mustard or chipotle, since their relationship would be a little spicy but not eclipsing the sweetness of the core (both the bread and the ham).

For the horny version: Shigeo would be the driving force here... At the beginning, anyway. He'd want to shut Reigen up from all his pent up resentment, so he'd probably make him deepthroat him in the sandwich. Mob would feel possessive of his shishou, so of course he'd be the one to "claim" him from behind, effectively spit roasting Reigen between the both of them.

I think at one point though, Reigen might take the reigns again and remind both of them why he's their shishou after all. This meaning even if he bottoms he'd guide them and occasionally be more dominant etc.

I need a ShigeMobRei sandwich with urgency punching the wall

It worked lol! I'm more of a 'individual songs enjoyer' and don't tend to follow artists/groups that much, so I'll name some songs c:

1) Magnetic by ILLIT (I've been playing this on repeat for the past two weeks orz)
2) SHIVER by the GazettE (I'm back on my Black Butler era, so)
3) Terribles Terrores by Say Ocean and Sputnik (I've liked Sputnik's music since highschool and this song dropped last year, hehe)
4) Sacrifice (Eat Me Up) by ENHYPEN (I love the mood/vibes of the song, and the dance coreography is also so cool and dramatic)
5) Comedy by Gen Hoshino (chill vibes, fun, helps me practice my Japanese)
6) Tapestries and Tomes by Julian Schoming (this song makes me feel like I'm inside a dramatic fantasy story)
7) 99 -sajou no hana arrange- by MOB CHOIR and sajou no hana (IMHO the best version of Mob's first opening)
8) FEVER by ENHYPEN (vibes + the coreography is so cool)
9) Scaredy Cat + Blueberries by DPR IAN (vibes vibes vibes)
10) Russian Roulette by Red Velvet (I listened to this song in 2016 and it altered my brain chemistry ever since. Aka, i love it)

Ahh that's a hard question for me, since I tend to be very strict with my own drawings...
I'll attach the pieces on twitter, but I think I would say: one I made of Dio and Jonathan underwater back in 2021, my 27 page comic based on one of my favorite JonaDio fics ("How it could be, how it should be"), one of Reigen and Mob eating ramen (since I don't tend to color all that often and I liked how that one came out), and maybe my One and Only One zine piece, the three-page comic.

Two honorable mentions are a one page comic I did of age swap Reigen meeting Shigeo/???% for the first time (I liked how the paneling came out on that one), and a traditional sketch I drew of Mob hugging a crying Reigen from behind (because I liked how the overall poses came out on that one). But yeah :'D

I think mainly the different dynamic possibilities between a Mob who never got the guidance and reassurance he needed during his formative years (and thus lacks a grip on his emotions + didn't develop the sense of morality of his canon self) and a Reigen that lacks the life experience of his canon self, which can show him to either still be excited about his interests with naivety or exploring his potential back story and family dynamics.

I also really just like the concept of "bratty, overly loud and needy of approval teenager gives lectures to emotionally stunted grown adult who is fully capable of killing and is fiercely protective of his disciple", haha