Dilucs Birthday

After

(a few days later)
Diluc walked up to the KoF headquarters. According to Jean, Kaeya had left him something before he died. He walked sluggishly, the civilians gasping as he walked by, some offering their condolences, some turning their heads rudely. Rumor had gotten out that he had been the one to kill his brother, Mondstadts beloved cavalry captain. He got to the tall building and walked inside. To the left was Jeans office. He knocked and was admitted access.
"Hello, Master Diluc.." Jean said kindly.
"Jean." Diluc replied.
"I'm terribly sorry for your loss, sir, but-"
"Don't call me sir."
"Wh-"
"Just- just don't."
"Uhm... okay. I called you here because while clearing Kaeyas room, we found this." She handed him an envelope addressed to him in his little brothers sloppy handwriting. He took it gingerly, careful not to rip or crumple it. He took a letter opener off of Jeans desk and slid the envelope open.
The letter inside read:

Dear Master Diluc,
If you are reading this, it means that I am gone. My current mission is more dangerous than usual, so I'm writing this to you in the hopes of explaining everything. I've written a letter for every dangerous mission I've been on. Just in case. I want you to know this. I was too cowardly to apologize to you in person. On that day, when you tried to kill me, I wanted you to. I'd rather have died than have to choose between my two lands. But alas, you spared me, and I ended up dying anyway. I forgave you many years ago. I still consider you my brother. I've been so loyal to the Angels Share, going almost every knight, in the hopes that I would see you. I miss when we were young, when we were still happy. And I'm sorry for keeping that secret, and I'm sorry for telling you when you were so fragile. I'm sorry for all those years that I never apologized. I'm sorry for hurting you. I consider you a brother, and I hope you consider me one too.
Love,
Cavalry Captain Kaeya of the Knights of Favonious