A/N: The symbolic meaning behind almond flowers is 'promise'.
The first promise they had made, under the almond tree, just as winter was melting into spring.
"I'll always stay by your side, Yuu."
That was the promise Lavi had made with him when they were still children, and Kanda had believed him.
True to the his promise, they were always together, by each other's sides. Sparring, eating, bathing, they sometimes even shared a room at night. They were never without the other, and nothing will separate them.
Only time will.
As they grew older, Kanda became more conscious of their relationship. They were not children anymore, free to do as they pleased. What would people think of them? He was a Second Generation Exorcist, living tomorrow's time as today's. But Lavi still had a long way to go after the war. He began to distance himself away from Lavi, and always gave Lavi the cold shoulder when he got too close, wanting Lavi to forget that promise.
But Lavi was never discouraged. He didn't mind the death glares that Kanda had sent his way every time he tried to hug him, the pissed off "Don't call me Yuu." every time he addressed Kanda by his first name, or the way Kanda would ignore him when he was waiting for him by the door. Lavi never cared, because he remembered their promise.
Until one day, Lavi disappeared.
He had been sent to China to look for General Cross, together with Allen and Lenalee. Good, Kanda thought. At least there was no one to invade his personal space now.
But he hadn't realized how badly he had missed Lavi.
It was another winter, and the weather seemed colder than usual. For the first time in his life, Kanda didn't want to go on a mission. But he had his duty to do as an Exorcist, so he still had to go.
The mission went badly, Kanda's heart wasn't in the fight, and he suffered multiple injuries because of his absent-mindedness. But he still managed to retrieve the Innocence, and that was the only comfort he had.
Somehow, his injuries were healing at a much slower rate than usual, and he was forced to spend more time than he would have liked in the hospital ward. Looking out of the window, Kanda could see the almond tree that carried the weight of their promise.
Where were you when I needed you the most?
As days passed, Kanda's injuries had slowly recovered, and Lavi still wasn't back from his mission to find General Cross.
My life seemed strangely empty without you.
Despite Lavi's absence in his life, Kanda had more pressing issues to deal with. Komui had summoned him to his office one day and told Kanda with a solemn expression on his face that he probably wouldn't have much longer to live if he continued to use Sangenshiki. And Kanda replied with an equally expressionless face that that was beyond his ability to control.
After that little episode that ended rather badly, Kanda's life returned to normal. But he pretended not to notice the additional Finders assigned to him during his missions, he pretended that he didn't miss Lavi at all. He increased intensity of his training, to make up for Lavi's absence, and tried his best not to think about the promise they made, so long ago, under the almond tree.
That was what you've always wanted, wasn't it?
The next time Kanda saw Lavi again, they were in Japan, and Lavi was busy getting trashed by Tyki. He found it rather surprising that it hurt to breathe as he watched Lavi being beaten down once, twice, he found himself taking the blow for Lavi before Lavi was struck a third time.
He also didn't miss the way his heart ached like it was pierced with a thousand knives when he saw the battered state Lavi was in.
After rescuing Lenalee, Kanda didn't forget to threaten Lavi with the usual "Call me by my first name again and I'll kill you". He saw the hurt that flashed across Lavi's eyes, and his heart broke a little more inside.
I'm sorry, but I don't have much more time left. Don't waste your time on me.
The battle continues in the ark, and the first Noah they meet is Skin Boric. Kanda decides to stay behind and fight Skin one-on-one, and told the rest to go ahead without him. Of course, Lavi wouldn't be Lavi and Allen wouldn't be Allen if they had gone without any 'persuasion', so he had to 'help' them make up their minds.
"Promise me, promise me that you will catch up with us."
"I will." If my time doesn't run out before then.
That was the second promise he had made, one that destined to be broken as he activates Sangenshiki again.
He had defeated Skin, but he was also left too weak to move. While the room crumbles around him, he thought of the two promises he had made, and how he couldn't keep any of them. He thought of the almond tree still standing in the woods behind the Headquarters, the promise that seemed like several lifetimes ago. He thought about Lavi, and hopes that Lavi would understand and maybe forgive him for breaking his promise.
As the room collapse into total darkness, he pressed his lips into a thin smile.
I wished you could've known.