It should've been me...

He could still hear it... The gunfire... The smell of gunpowder filled the room, followed by the distinctive iron smell of blood. John fell to the floor in front of him after taking the shot that was destined to Sherlock, it all happened so fast and yet, in Sherlock's eyes, it happened in slow-motion. Sherlock didn't run after the man who had just shot John, his top priority was his best friend, he fell to his knees and immediately applied pressure on the wound. He deduced the bullet had most likely pierced the left atrium of John's heart, giving him a 2 to 12% chance of survival.

"John. John, I need you to stay awake, okay? Do not fall asleep, no matter how tired you're feeling!" Sherlock pleaded his friend, tears forming in his piercing blue eyes.

"Sh...Sher..." John tried to say Sherlock's name weakly.

"I'm here John. Please don't try to talk, keep your strength as much as possible. An ambulance is on the way, okay?" Sherlock tried to reassure his friend as he sends Lestrade a text, telling him about the situation.

"Take...care...of Rosie...for...me..."

"Don't say that like you're going to die! You'll... You'll be alright! We will go back to the flat TOGETHER and we'll take care of Rosie TOGETHER. Please John... Rosie needs you..." Sherlock says with a trembling voice, tears slowly falling from his eyes and landing on John's already pale face.
"I NEED YOU! Please John... Don't leave us... Don't leave me..." Sherlock begs, what will he do without John around? What will happen to Rosie? The little girl had already lost her mother, she couldn't lose her father too. And yet... He could see John's life slowly fade away, his breathing was slowing down dangerously, his body temperature was dropping as well.
"John... Don't leave me alone again..." He begged in a strangled sob, John's hand weakly squeezed his own.

"Sherlock... I'm...sorry..." John whispered, tears falling from his eyes. He closed his eyes for the last time, taking his last breath, the last image he ever saw was Sherlock's face covered in tears.

"John? John?! JOHN!!"

Sherlock slowly opens his eyes, exiting from his mind palace. It had been two months since John's death, the ambulance didn't arrive in time and John died in his arms, it was the first time anyone had ever seen him cry. Lestrade had to drag him away from John's corpse so they could take him to the morgue, Sherlock had begged, cried, screamed and kicked, he wanted to stay with John, he didn't want to leave him alone. Lestrade had cried with him that day, he promised Sherlock they would stop at nothing to catch the man who had killed John. He kept his words. The man was arrested over two weeks later when he was trying to leave the country with a fake passport. For two months, Sherlock was unable to leave his and John's flat, he wouldn't take cases anymore, he couldn't sleep nor would he eat anything at first. All he would do was go in his mental palace and take care of Rosie, John has made sure that if anything happened to him, Sherlock would be Rosie's guardian. Sherlock has grown very attached to Rosie, he couldn't be away from her for long, going in full blown panic attacks if he couldn't find her. He stares at what used to be John's seat for a while, he lets out a soul crushing sigh before willing himself out of his seat. He walks to John's old room, now Rosie's, and slightly open the door, just enough to peek in. It was nap time for Rosie and she was sound asleep in her crib, Sherlock lets a rare, small smile spread on his chapped lips before closing the door. He walks away from Rosie's room and goes inside his, he lets himself fall on his bed and grab a photo from under his pillow. It's a photo of John, Rosie and him inside the flat, it was taken when John moved back to Baker Street with Rosie after Mary's death. They all looked so happy... Sherlock's slender fingers brush softly over John's face, new tears forming in his blue eyes. When John died... He broke down. He cried to the point his eyes were burning and his throat was sore from all the screaming, if it wasn't for Mycroft's threats of having him sent in a psych ward and take Rosie away from him, he would have let himself starve to death. He couldn't lose Rose too. She is all he has left of John, if he lose her too... There's no telling what he would do. Sherlock holds the photo close to his heart, letting a few tears fall from his eyes freely. He wasn't able to go back on John's grave since the funeral... He just couldn't bring himself to do it. He blamed himself for John's death too much...