@choberr here's the wholeass post about the logistics of sunisa in world trigger but since it got hella long i'm putting it under the cut
sakura defo is above average overall, methinks. his combat capabilities are not yet on par with a paralegal military soldier's skills yet (those he'll need to learn as he gets used to triggers and team fighting) but he has really, really good control over his body + he's developed a flexible mindset that allows him to adapt to the conditions of a fight (bc he never knows when he'll get jumped) and those definitely do come in handy when he's training to become a border agent. in terms of trion, i'm gonna go on a limb and say he's pretty high, maybe a solid 6-7 on the trion scale. whether or not he's a 6 or a 7 depends on whether or not i want to make his appearance a result of a Side Effect in this AU. on one hand, it'd fit the themes of "the things that make you unique don't make you strange" that wind breaker likes to perpetrate using sakura and the general acceptance of makochi's citizens, but on the other hand, it feels almost hand-wavy, just making sakura's appearance be a result of a side effect. besides, what the hell would that side effect even be that it'd affect his hair and eye color???? oh, and in terms of roles he's an attacker. no doubt. scorpion main to be exact, maybe also gets some asteroids to bail him out in a pickle?
now that i've got the boring logistics out of the way, onto the juicy stuff: what the hell gets him to enlist into border? answer's simple: it's so he feels like he's worth something.
sakura's already established himself to be a person that sees his own self-value as equivalent to his combat ability, so i wouldn't be surprised that he joined the place that allows him to both use that combat ability and be seen as a net positive for society in general. he's signing up the moment he finds out about them. he may have convinced himself he doesn't need anybody, but i feel that he still wants to be accepted somehow. that's why he came to furin after all, yeah? he wanted to take the top so he'd have a place that proved his worth, even if that worth meant carving out a place for himself using fear. unfortunately, border– just like furin– is a moshposh of unique personalities, and with the existence of side effects here, i'm sure that they wouldn't even bat an eye at his unique colorations. "oh, it wasn't a side effect? well it can't be weirder than the side effects we've already got. who cares about whether or not you don't look 'normal'? i don't think anything can get less normal than the things we fight daily" <- general consensus at border about sakura's appearance, probably. besides, since most of the wind breaker character's are gonna be here too (i assume), i'm also sure they're gonna be accepting of his appearance regardless of whether or not it's a side effect. unfortunately, this acceptance has the additional consequence of Confusing The Fuck Outta Sakura.
it might also be a little bit harder for him to actually open up because there's a level of transaction between border and him: sakura fights for them, and in exchange, he gains a place to sleep, eat, and (according to him) begrudging acceptance from the people around him. i doubt he's willing to open up as easily here, because he has the excuse of "they're just my coworkers" to fall back on, but i'm sure that, like in canon wind breaker, nirei and kotoha and ume are there and waiting with sledgehammers to smash through his walls (+ forced proximity with at least 2 other people when he's inevitably shoved onto a squad in order to rank up means he's GONNA get sunisa'd anyway).
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suo suo suo. suo fucking hayato, what the hell do i do with you. okay obviously he's gonna have high trion levels, perhaps a 7-8. i don't think he'd have a side effect, but he's definitely going to have some high baseline combat abilities due to past training and the like, but i also believe he's gonna be more of a gunner/shooter in this scenario (because we've established he has a good noggin and he might as well use it because getting in close and personal is not exactly the best kind of way to fight against extraterrestrial creatures with weapons beyond our current technology). he's also smart enough to use viper, methinks, though calculating their trajectory during live battle and composite bullets might be too far of a reach for his skillset for the time being. maybe him being a little bit adept in the kogetsu would be cool too! ugh, nvm i'm making him an all-rounder because he deserves it.
i believe his eyepatch, in this universe, is a result of the neighbor's invasion that happened a while ago, and him getting caught in the crossfire is what causes damage to his eye. that incident probably also scarred him by taking away people that he cared about, so the whole "need to be an adult" thing suo has going on can be translated into survivors guilt for not being able to protect the people he loves and is defffffffinitely going to leave him with some really bad ptsd as he continues to grow up and continues to affiliate himself with border. he is definitely orphaned because of the incident and is taken in by border, like hana was in the canon wt series
here i'm assuming he's already a part of red chanpuru (no. 1, 2, 3, whatever) as a trio w/ rakta & bacchus in either mid or high tier B-class, but because of some complications (what are the complications? idfk), he gets put with sunisa when he's drifting around trying to figure out what to do since his original squad is off limits for the time being. i can also see the red chanpuru being a part of the bkk-gai branch of border hq (kind of like suzunari and tamakoma) who are specifically on the kido faction. suo himself doesn't really care for it, so whether he's on the kido faction or the shinoda faction honestly depends on whichever squad he decides to stick with. there's probably also going to be some level of drama considering suo's previous allegiances but it'll get sorted out pretty quick considering they can't have MORE infighting between border: the faction conflicts are already enough.
since suo's an orphan here i wouldn't be surprised if he's one of the older kids that cares for the younger ones in the border-run orphanage, kind of like rokuta in wt. it'd mimic his role as an older brother/kyoudai figure within the dojo, except significantly less child exploitative here because border does actually care for their younger combatants and red chanpuru in the wind breaker canon does not T^T i'm so fucking glad red chanpuru aren't given as much authority in this world given that they're more of the token bkk-gai branch squad instead. thankfully.
with the whole tutoring nirei thing, i think it's more about teaching him how to be more autonomous during rank wars? since they're mostly two or three way squad battles, nirei learns from suo (who's been a B-ranker for significantly longer) how to be useful during team matches and the like. for this to be a thing, though, that kind of means suo's been sticking around sakunirei since their c-rank days, which is probably how sunisa becomes a squad anyway, so it works i guess.
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nirei is easy. nirei is average. he's got average trion levels, like a 5-6 probably, except he's got zero fighting background and is kind of flailing about which role he'd be best suited for and how it clashes with the roles he actually wants to be in. i'm leaning towards him being an attacker with a scorpion just in case for now, but i can also see him becoming a shooter if decides to be one (and it helps out with the whole suo being his teacher thing). i'm also assuming that when he gets trained, he'd get training on both controlling his trion body more and how to effectively utilize his triggers in a fight, though that stuff i think comes par for the course as he continues his time as a c-rank trainee.
his strong memory stays a thing in this universe though: definitely comes in handy when creating preset strategies or helping remember about previous matchups and strategies that have or have not worked with squads that they're pitted up against during the rank wars. he basically never needs the tablet because he just remembers everyone's names and faces and it kind of freaks sakura out but it's okay LMAO debriefing before a match is easy with nirei around lol.
he'd definitely join border because he wants to be a hero of justice just like in canon, except also like in canon, he ends up being stuck in c-rank for a while until he manages to learn the chops and properly upgrades into b-rank when he finds sakura and suo and starts to be more confident in the training route he's taken + him finally becoming determined (and shameless enough) to ask higher ranking agents a bajillion questions to help himself improve. i see him being a little bit more hesitant to interrogate people like in the beginning of the wbk canon, but just like wbk nirei, wt nirei eventually gains enough self-confidence to just start hunting people down for info LOL. nirei still has his notebooks, yep, those are his soulmates and they will never leave him in any universe.
him being the emotional glue of sunisa is also not gonna change, because there's no world i can see where he stops being the token Relatively Well-Adjusted one out of the three, and i don't see suo "survivor guilt 5000" hayato and sakura "my worth is in fighting and without it i'm worthless" haruka being the mentally adjusted ones anytime soon.
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okay general factoids GO:
like i said in the ask, they're definitely gonna be shinoda faction unless something happens to convince them to jump ship. the shinoda faction and tamakoma factions are mostly on neutral terms anyway so i don't think any of them would have hangups about it save for maybe suo because. y'know.
their general formation is currently shaping up to be two attackers with a shooter backing them up, or two shooters backing up one attacker. i can't really see any of them being a sniper? but if anyone's gonna be a sniper it's gonna be suo.
sakura's coming to border from outside of mikado like he joined furin as a person that came from outside of makochi. obviously.
umemiya and bofurin in general are probably just going to be split between hq or being branch members.
for the four kings: i can see ume, hiiragi, tsubaki, and momose being combatants while mizuki is the operator (because he was the one that spearheaded that whole military ass meeting), but if you have a different opinion, i'm alllllll for it.
OH!!!!! speaking of operators, kotoha's definitely gonna be sunisa's operator. ume's gonna be like "i'm entrusting her to you guys! play nice, okay?" when introducing them lol