Ok so it’s a bit of a mess of an idea and a little out of order but
World trigger AU ( inspired by “Meeden birds Return home by CourageousPrincess https://archiveofourown.org/works/48537382/chapters/122432476)
~Chika and Osamu get kidnapped by neighbours and manage to escape and when on the run they encounter Yuma in the neighborhood
~ Yuma still has his black Trigger
~ Osamu and Chika have neighbour triggers
Osamu -> stealth based trigger which can form small Trion soldiers who can use the wires and bombs the trigger has It is also equipped with a gun and shield
Small spider/crab like trion soldier who holds stuff in its back It can equipped with one ability at a time, or have an open slot. Osamu can make at most 5 at the same time if he puts all his trion into them they do not go away if he’s in his real body but he can dissolve them back into his trigger to regain the trion unused. The “spider” soldier has a some what dense shell which is weaken when invisible. The user can retain audio and visual information from trion soldiers.
Chika -> has a medium range trigger with a machine gun and heavy shield with a special ability to create a stationary heavy artillery
^ I wanted to open experience and reference to their border triggers since I like their canon fighting styles but not be like “ hey they found the exact trigger build on the run” it doesnt seem fully realistic and also give fun changes.
~Chika doesn’t always go for the “killing” shot right away but she can, her and Osamu learned it’s better to be underestimated. To show as little as possible to make it through an encounter.
~Chika and Osamu meet Yuma when they are actively hiding from an enemy and they just barely successfully avoided them, Yuma was already in their hiding spot for some reason( maybe he just stopped for a break) and he greets them with a “Yo!”, he is on guard but playing it chill but Osamu notices his readiness but him and Chika can’t fight unless they want bring their enemies back to the fight. So ever tense atmosphere, Yuma will ask what they are doing and Osamu choose to be honest and say they are hiding and with his honesty Yuma is less on guard. ( this is the boi who is kind of on a suicidal mission) this breaks the tension where full trust is not build yet but it’s the beginning of a relationship.
~the trio + replica travel together specially when Yuma mentions border and Chika, Osamu learn about bit about Yuma and Yuma learns a bit about them, they grow from companionship to friendship
~before making it to earth they encounter Aftokrator on another country and they lose replica to save Chika and Osamu
~ they would make it to earth after the Aftokrator invasion( I think I might just say timeline what timeline and make it happen earlier in my AU)
- Hyuse is already stuck on earth and makes a deal with border before the trip come to earth
-when arriving on earth in was Yuma’s job to keep them undetected and Osamu to put together covers and documents
(His and Chika old stuff and see if they can find anything for Yuma, surprise his dad made some stuff but they need to make up other stuff)
~the trio join border for a number of reasons
•Having trigger to defend themselves without having to fight border
•to find out about Yuma’s dads friend
• to find Chika’s friend ( +later her brother)
~Chika does decide to become a sniper because she likes it better
~Osamu tells Chika and Yuma to try and not bring to much attention to themselves. Chika succeeded with her small frame and hiding behind others
Yuma does not think to hard on how fast he bet the practice trion soldier and got a disappointed sigh from Osamu
^they do rush to B-rank but try not to show as little as their hand as possible
~Osamu starts with a gun but moves to becoming a shooter instead, he ends up going to the engineers and researching all the trigger options
~Yuma ended up choosing his triggers via Osamu suggestions and watching B-rank solo matches
^ during rank wars people try to challenge him or he challenge other which Osamu and Chika will stop if they are there so it becomes known to those wanting to fight him to get there alone
~Chika used lead bullets almost right away and the basic sniper ( cannon girl hidden unless really needed)
^they still want to get in the away mission as soon as possible
~ Jin does casual approach them but most focus on telling them about the border groups and pointing them towards Tamakoma, this does put all their guard up. Jin would offer an operator and have them “run into” other members of Tamakoma with Osamu meeting them he grows more comfortable and eventually tell them all about them (Osamu, Chika and Yuma)
*they don’t join Tamakoma right way but they do join close to half way through the B-rank wars
~after a lost (they would be part of Tamakoma at this point) they approach hyuse. Osamu would start by throwing him off his game by asking him if he was a high ranking official or have connections to a high ranking official. Hyuse would cautious confirm he does and asks how and why which leads Osamu to saying Aftokrator took something of theirs and they will help him get home if he helps them get it back.
^later Hyuse would learn about Yuma, Chika and Osamu
~there is a scene I imagine with Yuma leaning about the hopeless of his mission and Chika and Osamu grabbing each other his hands and looking at him with determination and fierceness and Yuma sighing and saying “ I guess my life hasn’t been just mine in awhile, I’lol follow you guys wherever you go” and similes at them. 
