Both of them prepared to go through JYP's auditions separately, but the JYP audition judges decided to put them in a team together to audition (they met each other at that moment)
They both arrived #1 during the recruitment and they were both the same age (JB is an early 94'er and Jinyoung is a 94'er too)
Since they had opposite personalities, they were supposed to be training together, but begged JYP to let the train separately
But JYP still thought that putting them together was a good idea so they appeared together on Dream High2 and later debuted as singers under JJ project
At that time, when they were under JJ project, JB used to be even more blunt and cold, while Jinyoung used to be more lively and bubbly. They kinda looked like those families with 2 sisters with opposite charms? (though JB's parents said he had a lot of aegyo..)
There was this anecdote about them when Jinyoung was doing aegyo and JB went "What are you trying to do? If you're a man act manly!"ㅋㅋㅋㅋㅋㅋ
However, it's not like Jinyoung was the submissive type either, because there was such a discord between their personalities, they ended up fighting a lot of times
JJ project dissolved and both of them were sent in a vacuum.
In 2014, they debuted again, not with 2 but 7 members, it was GOT7
However, when GOT7 debuted, Jinyoung and JB's auras changed quite a bit
JB became a bit more lively and Jinyoung became so calm, it's as if they combined their personalities??
When they were under JJ project, JB never laughed at Jinyoung's jokes, but now, he's receiving them pretty well ㅋㅋㅋ
And they learned how to lean on each other. It's not like they're friends with each other, but they learned to understand each other more deeply since they spent so much time as trainees together and somehow influenced each other.
During that time, Jinyoung also started reading a lot of books, and he learned that from JB
Here's Jinyoung before he joined JYP in his dance team
original post: here