I think the point of introducing Vincent, is to show that :
. Jack had a lover waiting for him when he enlisted, and he was planning to quit the army when the war would be over
. Jack enlisted to protect people like Vincent, I think that means civilians.
. Jack couldn’t quit Overwatch after the war ended. He took the job, because he wanted to keep protecting people. (and probably because Reyes didn’t want it and someone had to do it)
. He sacrificed his (propably first) love for the world and Overwatch.
Can’t people see all the sacrifices Jack made? And all that self-sacrifice for what? Overwatch being spat upon and ended being blown up???
No wonder why he is grumpy and pissed.
(God I love this man even more now ![:heart:](https://d74zh8edaijub.cloudfront.net/en/overwatch/images/emoji/twitter/heart.png?v=6" ":heart:")
)