I apologize if you've done this before, but how did your OC's meet their significant others?
oooo! I actually haven't done this before! Alright so I'll do this for a few of them.
Daniel Stark: Daniel met Peter after Peter had become Tony's 'intern'. Their relationship at first was...NOT pleasent. Daniel found Peter incredibly annoying and hated that it seemed like his dad had found a new 'son' to replace him. Peter ended up the victim to Daniel's magic a few times before things got to where they were.
Robert Barton: Robert and Clint met after a mission gone wrong. Clint had to be rushed to the nearest medical facility which was just a hospital nearby. At first Clint wouldn't let anyone near him but Robert didn't care, he was going to help Clint and fix him up even if he had to wrestle him down to do it. Clint had to admit...he found Robert interesting and soon Robert became the head doctor for the Avengers.
Kade Wheeler: Kade met Paul after Jacob had invited the boy to LaPush as a welcome. When Kade agreed and went he met the entire pack...and that's when Paul imprinted on him. Paul and Kade butted heads at first. Both strong headed and not wanting to back down it only made things more interesting.
Lux Shepard: Lux met Kaidan on a mission before being recruited to the Normandy. Anderson wanted to know how well the two of them would get along so he had them on a basic patrol mission. It ended up with both of them stopping a pirate incursion. The two worked VERY well together and Anderson knew he made a great choice.
Gideon Wayne: Gideon's mom worked at one of Gotham's top hospitals. That hospital was also funded by the Wayne's and Martha Wayne would visit regularly to check in. During one of those visits Gideon met Bruce and the two became close friends to where they'd often have playdates and sleepovers. Gideon and Bruce were literally the childhood friends to lovers trope.