Crow you ask the hardest questions because I really want them all.
I love first time scenarios, idk, it's one of my always go-tos & part of the reason for that is because I love thinking of all the different ways it could go & being unable to pick a fav!

For like ... post-canon when thinking abt what I want for them (= a happy working relationship) I do like all the slow, cautious, long-winded negotiation-heavy build-ups. And I mean it's fun because it'll inevitably mean sexual tension or outright frustration.
Also depends a little on definition of first time, any sex or specifically penetrative, because I think the time inbetween could also stretch so frustratingly long for both both sides~
Even then it could go so many different ways though!! And frustratingly long could be half a year or three. Because even though I love horny Reigen who can't wait any longer, I do think if he really had his mind set on it & was convinced it mattered, he would manage to wait. And he would make Mob wait, even if he hated it, too.
Also, office sex is undoubtedly hot, but I prefer that for not-first-times if it's supposed to be a good one khdfjlf The best place is Reigen's shabby little apartment of course. I imagine Reigen to not really prefer it there, I imgine him to not even really want to invite Mob there. But I love the idea of Mob loving the place, because it's small and Shishou's & it feels secure and they're talking hushed closely together in Reigen's single-person bed while Reigen feels up Mob's thighs and Mob feels up Reigen's chest...

I would say the above is headcanon territory, but that aside there's also so many other scenarios I'd love.
The feelings-so-genuine-they-barely-have-doubts ones... Less realistic, but I think they'd be so sweet <3 Them just losing all restraints once it's clear it's mutual.
Or fun this-was-supposed-to-be-a-massage-but-oops-it's-sex situations & the like.
In any case where they're remotely healthy, I think Reigen would be cautious though, gentle but also very alert to Mob's reactions.

The fun times aside...
Some fuck-or-die scenario first times can definitely be so incredibly, painfully good. But I do prefer them with pre-existing tension, instead of one/both of them really wouldn't want that under any circumstances. Like a forced feelings realization.
& then of course there's the awful kinda scenarios deep in thinking-via-dick territory, but those are not 'preferred', so I'll end it here :D

YES PLEASE
I was never into food in any romantic or sexual way, though I didn't mind it either, but since food is such a theme in MP100 and the fact that Mob does casually feed Reigen in canon makes me go positively insane over tropes like that!!!
I love the casualty about it tbh, but yeah man, I think Reigen should very casually offer food and Mob should very casually accept it and now and then Mob should lick Reigen's fingers clean and un-casual Reigen immediately by it even if that's not at all what he meant to do.
Mob probably would be so oblivious to it anyway. He gives his fingers a lick, then gently sucks on them for just a moment & Reigen has to keep it together.

Honestly most factions are just whack & I'm always like ... I don't want to associate with either of y'all!!
But that's part of Fallout's charm I think lmao. Everyone is at least a little bit terrible.

In general I love how the franchise mixes things, like the concept of knights and religious aspects used in a post-modern military context for the Brotherhood of Steel & while everyone including me hates Cesar's Legion, from a design standpoint I think they're so fun. They've just become a normal part of the game by now but when I first encountered them seeing Roman Empire stuff in a retro-futuristic post-apocalypse game was unexpected to say the least lmao
I've played very little of Fallout 1&2 but I know there was a Yakuza fraction too which I hope to maybe see back for if a Fallout 5 ever comes around, I think that could be very fun too.
The Enclave sucks too, but shout-out to them for ED-E <3 It & Rex where my always companions in my og NV playthrough. I love it's little battle fanfare & beeping!! So cute!!
& I'm a bit fond of New Vegas' Boomers. They're random & they're also whack but for my other OTP's Fallout AU, I headcanon one of them being from there so there's heightened interest haha... And I love their bomber jackets.

Which kink tier list?? Send a link I wanna make it!!

As for the questions, my fav band is from my country, not gonna name them here haha. Other than that I dislike declaring definitive favorites, but I'm just gonna say The Offspring is certainly among my all-time favorites & one of my most listened to bands because I can always go back to theirmusic and... Hmm... It doesn't necessarily always make me feel happier but it has never lost the ability to give me a certain sense of drive? I feel more enthusiastic I guess. My favorite album of them is Smash and I predictably love Come out and Play & Self Esteem, they're popular for good reason okay. xP Third big fav is Bad Habit & I can't even drive LMAO its just such a jam!!

Hmm, in my headcanon they do have a clear preference for Reigen domming later in life, wheras I'm actually quite open for top/bottom switching & think they could both enjoy it both ways, even though they're both much more used to Reigen topping. I'm just extremely picky on how MobRei happens.

Tbh, it's hard to say what MobRei I like most because of that, it's honestly much easier to say it by comparing it to what I can't have... orz
But I'll try.

Most importantly, Reigen needs to still lead in a way. I said it before, I don't recognize them as the ship I fell in love with when the dynamic is completely different. I need Reigen to give Mob safety, no matter who tops or bottoms. (Which does not mean it can't be mutual!)
Then I need them to both want it, but especially Reigen, which is why I prefer Reigen initiating. Though I do think it can be kinda cute & funny if Mob just really wants to top, but for me it won't happen until Reigen allows it to.
My favorite top!Mob is obedient, eager to please & working to be praised. Maybe accidentally rough sometimes without even knowing it when he gets a little too excited, but never out of ill will. And he's all ears & loves to learn from master. So - a dog, all around. He's a puppy top to me.

Mob is kind & sweet & by the end of the series he is also better at expressing that & at allowing himself to be happy. So for anything post-canon, which MobRei always has to be for me, I need to be able to see that in Mob.

Yes!!! I'm looking forward to the next Mobstocking ever since I joined the fandom & barely missed last years, basically!!

I also definitely have some more RM cosplay goals.

Other than that, I'm pretty open to whatever comes along, if MRM week happens this year I def want in even though I can never make all days for fandom events.

I just wanna keep creating and enjoying what other do & keep chatting with people enjoying some of the same things I do <3

That said, the "while a mobsai fan" status is bound to last.
I might not be forever as productive (for my standards) but I'm sure to stay. MP100 has had an impact on me barely any other series had & I don't call something my OTP lightly. I've been obsesed with many ships, but ReiMob is the second in 15 years to ever make it to that title. I'm ridiculously in love. I'm not going anywhere.

After too much thinking, massages.

The question short-circuited me or smth, decisions about such important things are hard!
One of my biggest & most fail-safe kinks is somnophilia, but if it was infinite amounts I would want to pick smth both parties are awake for I think, haha...

So, massages maybe, because
1) it fits their canon, ofc
2) I love the intimacy of intense physical touch
3) you can go a LOT of different ways with massages!

It's such a versatile trope, it can be undoubtedly hot but it can also be soft at the same time, or it can be frustrating and who doesn't love unresolved sexual tension.
It can have focus on your favorite area wherever it may be, so body worship etc kinks are easy to blend in.
It has a nice predetermined dynamic of giver/receiver & you can do a lot with that too, be it in a caring direction or in a darker one.
And it focusses on Reigen's hands. And man, do I love hands & Reigen's are pretty far on top of the list...

I've loved & wrote massages before RM, so I felt instantly blessed with Reigen's scams...

This will be so long and rambly. ˋ( ° ▽、° )

Domesticity for ReiMob probably. Guilty Reigen tropes too obviously, but nothing gives me life like fanworks that just look like they could belong in canon, with Reigen & Mob just ~being somewhere~ & ~doing something~ that's probably either spirit or food related. Oh yeah I can also never get enough of food emphasis in mp100.
RM feeding each other... RM being close in casual ways... RM being close in strange ways, both from an outsiders perspective even pre-slash without noticing it themselves as well as in private.
Reigen being utterly devoted to Mob in the most insanely casual way. Mob being devoted back in a somehow entirely different but just as sincere way.
Reigen teaching in any way possible, I love everything where he instructs Mob & I love that there's so much of it!! Teaching him in bed, teaching him how to shave, tie a tie, how to cook, where to buy to get most of one's money, how to apply for jobs!!! Everything!!! And in the very most cases it's not unsolicited, Mob looks for advice in Reigen more often than not, still well in his 20s. Except for the Yakiniku incidence, Shishou's advice has never failed him.

My fav SasoDei tropes are they are fucked up and doomed lmao. And very obviously I'm #1 aging-Deidara-down fan... Gotta make use of that age gap.
SasoDei is hard to pin favorites down to even more, because I've been in this pit for 15+ years and probably rotated these blorbos through each and every trope I ever enjoyed. (and they are at fault for so many of my fiction kinks...)

But I realize I like a lot of the same tropes but in a contrary flavor for these two ships...
ReiMob devoted codependency that is questionable but so so sincere at its core vs SasoDei codependency in the most unhealthy obsessive way possible
ReiMob loss of boundaries because they're just too comfortable around each other vs SasoDei loss of boundaries because both or one party are forced to
~15 year age gap as a "against all odds" in ReiMob vs "it's even more fucked up than it sounds" in SasoDei
Reigen taking care of Mob because he decides to, because that's kind of his calling and he thrives doing so and he's so good for that kid vs Sasori taking care of Deidara because he has no other choice and he's fucking awful at it, even in the cases where he genuinely tries, he fucks this kid up so much worse than he already is
Reigen teaching Mob in all those lovely aspects vs Sasori raising Deidara into a child soldier (& tangential other ship, Jing Yuan & Yanqing a bittersweet spot inbetween these two)

Sexual trauma is a noticable trope fav for Deidara exclusively tbh, both inflicted by npcs for Sasori to deal with or by Sasori himself... That's smth I'm not really into in RM.

That said, I think I often make it seem like I don't ever wanna see SasoDei happy, but I love all the angst & suffering and killing one or both of them off, but inbetween all the doomed things, they also have immense power couple potential, which is a trope I will always adore about them!!
They are two bad bitches & even in instances where they're bad for each other, they will always be two times worse for anyone who'd dare mess with them & I think that's very romantic <3

I play both Genshin & Star Rail (Genshin has been a hyperfixation for 2 1/2 years until MP100 saved me), the Pokémon franchise will stay with me forever, big Zelda fan too, lately my Fallout love has been reignited but our PS3 decided to break just before!! Now I FINALLY have everything to make it work again and start New Vegas over (the AUs are going brr like crazy in my brain as well as everyone probably noticed), I love Survival Horror, Silent Hill is crazy dear to my heart (James Sunderland might be the og pathetic blond man that kicked it all off tbh...) things like Metro, Last of Us...
I also love Indie Horror games but I haven't actually played one in probably a decade lmao, horror playthroughs are my near-daily sleep aid now.
God I could go on and on and am so tempted to list specific games I'm emotional about, but yeah I'm honestly not very picky. I play a bit of a lot of things but also, I almost never finish a game. 〒▽〒
ADHD too strong I guess.
I also own a whole staple of games I really would like to play but still haven't... And there's even more I don't have but are on my list. I have too many interests to fit them all into my life OTL