Final Fantasy VII - Growing up together...

Is the real Cloud, the thing is that you can only join SOLDIER if you survive the Mako infusion process, the one which required you to be strong physically and mentally, Cloud was neither, so he had to join Shinra's military to get strong enough to one day get in.

After the Nibelheim incident he was not only infused with Mako energy but also with Jenova's cells with caused to develop a great physical strength, but due to him being mentally weak the process putted him in a coma that lasted 5 years, after waking up and due the time that he spend with Zack he started to absorb memories of him, even after that he was still in a unstable mental state when Tifa found him on Midgar, in where she told him that they were close and Cloud accepted that as the truth.

As Videogamedunkey said: “Final Fantasy Remake is the game where people who love Final Fantasy VII are going to realize just how fucking stupid the story to that game is.”

Funny thing to remember that they weren't childhood friends, Tifa barely noticed Cloud’s existence until he left Nibelheim at the age of 14 and by then they only talked a handful of times, Tifa pretty much fabricated the memories of being close to Cloud due to her own fear of being alone with Cloud being the best candidate because he was a part of her past.