Jin first.

Jin and Roy
Tied between Helly and Jin's relationship and idk nothing-

Jin and Poli
Yknow I haven't seen these guys interact with each other outside your yknow work (this can be said with well any RT member and Jin, apart from Helly but I just can't visualize the kinda of relationship these guys would have that well)
So I'm just gonna say the kind of people who are friends but you'd never know considering they talk a lot when no one watching, usually cuz they're up late talking about well, work.

Jin and Amber
Gardening buddies, in the little free time these poor individuals get they most likely spend time together sprucing up the center's garden.

Jin and Helly
I see them as having this kind of Strict Mother and Accident Prone Son kinda relationship. Like the kinda momma who would scold you for scraping your knee on the driveway by saying "I told you not to run." Yknow?

Jin and Mark
Again, barely interacted.

Jin and Bucky
This might be updated when I get my HCs  chapter together (which is in the far future but dw bout allat)

And OF COURSE Jin and Stacy
Met over similar strengths, repairing stuff. Jin probably being more skilled at that kinda thing probably gives Stacy pointers on how to do stuff correctly or quicker, and then they make out

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Helly next

Helly and Jin: already said.

Helly and Roy
Roy sees Helly as a younger brother and Helly sees Roy as that one cool older family member who's your role model for most of your adolescence.
They draw pictures together and despite Helly's drawing being, questionable, Roy still puts it on the fridge.

Helly and Amber
If Helly's crying he going to Amber first. Helly trusts Amber with a lot of things. And yeah Amber would probably pin his drawing to the fridge as well.

Helly and Poli
Poli is kinda like Jin in a sense, he's strict but he's not Jin-level strict. He'd still say stuff like "I told you not to do this." Yeah but he's like the fricking Dare Program you probably took in 5th grade, he'd teach Helly a lesson about why doing that is bad. (Literally everyone BUT Helly but ok)

Helly and Mark
These guys throw insults at each other every other day, but they don't hate each other. I mean they tolerate the other's existence that counts for something.

Helly and Bucky
I barely Interacted and can't think of anything

Helly and Stacy
They usually just have a conversation about the other's job when Helly is inspecting the emergency phones.

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Roy next, yippee

Roy and Jin: already said-ish

Roy and Helly: already said

Roy and Poli
Made for each other, all I gotta say.
Nah I'm just kidding. These guys are totally that one school "couple" that even when they were just best friends people were shipping them because of how close they were. If one is down the other is there to pick the other up in Roy's case probably literally.

Roy and Amber
Siblings for life, like they got that sibling rivalry feel to them that just doesn't happen but you feel it's about to.

Roy and Mark
"My bf's better" "Nuh uh" (Joking ver.

Roy and Bucky
Barely interacted.

Roy and Stacy?
Barely interacted.

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Poli next.

Poli and Roy: already said

Poli and Jin: already said

Poli and Helly: already said

Poli and Amber
Work buddies, like they'd pass each other up when going to places to patrol and kinda talk for a few minutes then do other stuff.

Poli and Mark
Barely interacted (I'm tempted to write M&B them out of this...)

Poli and Bucky
"My bf's better" "Nuh uh!" (Serious ver.)

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Amber next (probably not going to have anything here)

Amber and Jin, Helly, Roy, and Poli: already said

Amber and Mark & Bucky
Barely interacted.

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Mark and Bucky
Gay, made for each other, the equivalent of Roy and Poli but with less screen time.

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In conclusion, Jin and Stacy are underrated and Mark and Bucky need more screen time with the crew.