These boys grew up together. They knew each others favorite everythings, and they understood how different they were from each other.
Wally West knew how upsettingly uptight Grayson is, and Dick knew how annoyingly laid back his best friend was. They also knew that Dick was gay.
Our story takes place just a normal day, Wally and Dick walking together around the park, like they always do. Wally is generally eating some food they got off a food cart, and Dick was just really happy to be with his best friend.
"So, any guy in the world?" Wally asked, too busy eating to see the blush forming on his best friend's cheeks.
"Nobody really, Wally. I mean... I'm me..." Dick trailed off as he noticed an adorable tall brunette guy flirting with him from afar. For some reason, Wally felt a strange emotion as he watched his shorter friend flirt back. The guy and Dick started to talk to each other, leaving Wally to shovel food endlessly in his mouth to stuff down the sudden urge to punch this guy in the face. Dick wasn't gonna fall for this, Wally thought to himself, but quickly the guy had Dick trapped in his embrace. The half a second it took Wally to notice, only half a second later was he knocked out on the ground.
"DUDE!" The younger exclaimed, more confused than angry.
"Dude, shut up, and don't ask, I just got mad, that's all."
"Wally West... are you homophobic?" Dick looked horrified as the words came out of his mouth.
"I-I... I don't know...," said the ginger young man, trying desperately not to look at the younger raven haired boy as tears streamed down his face.
"O-Oh... I just... well... oh..." Dick tried to explain, without giving away the information to Wally that he was madly in love with him. Suddenly, Wally caught on.
"Dude... I... I'm with Artemis..."
Robin looked away from his beloved Kid Flash, "Save it... okay?"
"But.. I can't see you cry... I just... I can't. I don't know what's going on... but I care about you, Dick Grayson, so please don't cry." Wally offered a gentle smile, and opened up his arms to embrace his friend. Dick couldn't help himself but cry in this situation, feeling completely safe in Wally's arms. "I love you, Dick..."
That's the same point Dick woke up every time. He knew Wally loved him, but it was his secret. He would never tell Artemis, he couldn't do that to her. He knew that Wally had Barry tell Artemis his dying exclamations of love, but.. no one told Dick. He stopped trying anymore, and everyone was worried about him. He was taken to multiple therapists and psychologists, but he couldn't tell them the truth, because he's internalized Wally's love so deep, he's not even sure if that happened.
The more he thought about it, he realized how that seems like such an out of character thing for Wally to do, and even much more out of character for Wally to be gay. When Dick really thought about it, he's never flirted back with a stranger, and Dick has never cried in Wally's arms. This vivid dream turned into a memory, was the way Dick coped with the loss of his best friend, and the only person in this universe Dick Grayson could love.