Flashback:
While he truly did not mind taking care of his brother, Kaeya could drain him of his patience. Ever since their father passed away, he was the one to watch Kaeya. Adeline and Elzer were listed as their guardians but he was the one to finalize any work and to actually take care of his brother. Diluc noticed the changes his blue haired brother was going through after their Dad's passing. Unless you truly knew Kaeya and could look past the mask he wore, you would not have been able to tell the difference. The fake smiles, the new lying habit, and making himself shut down. He wanted to talk to Kaeya but he was afraid. Afraid that if he tried to talk about his behavior, Kaeya would run away from him, lie to him, or just completely fall apart. After a few months he noticed his brother become angrier, sadder, and at times he almost looked numb. It was as if he was watching his brother's light die just by looking him in the eye. One day, he got a message from an anonymous source.
Unknown: My my my, What an awful older brother you are. Letting Kaeya drink to his heart's content until he knocks himself out.
Unknown: Oh, are you ignoring me, Diluc? You'll want to check on Kaeya... Despite the fact he isn't home.
Diluc didn't get these messages until later and his heart nearly stopped. Instead of responding he calmly walked to Kaeya's room before knocking on the door. He knocked three times before he walked in when he received no response. Sure enough Kaeya was not there. He started to check every room, every hiding spot, any place he could have been. Diluc gulped as he pulled out his phone to text Kaeya.
Diluc: Where are you?
Diluc: Kaeya, why aren't you home? You did not have permission to go out anywhere.
Diluc: Kaeya, where the fuck are you?
Diluc wasn't able to sleep that night. He stayed up after texting Kaeya nonstop and calling his phone for the umpteenth time. At about eleven in the morning, Kaeya came stumbling in from their front door. "Where the hell were you? Why weren't you responding to my texts or calls?" Diluc scolded him. Kaeya only held his head "Diluc not so loud, I have an awful headache. Sorry, I thought I told you I was going over to Childe's place to study for one of our classes." Diluc looked him over and saw the bloodshot eye with an unfocused pupil. Diluc cursed in his head but knew this wasn't the time to talk to Kaeya about it. He needed to talk with Kaeya when he was sober and possibly suggest therapy. "Go to bed. You look like shit." Diluc sighed as Kaeya quickly made his way to his room. Tomorrow. He would speak with him tomorrow.
Diluc dragged Kaeya to the doctors after discovering the infection. The doctor quickly saw the young teen and gave him a prescription for antibiotics to kill the infection. Unfortunately the pharmacy was out of the pill form, so they only had the liquid form... grape flavored. Diluc decided to hide this fact from his brother seeing as he didn't exactly care for grape flavored things. In fact, he hated anything that even remotely tasted like grape. This was going to be fun. A few days after resting from the infection, Kaeya was going to an out-patient program as part of his treatment instead of going to school. Diluc was set to go back to school once he made sure Kaeya was all set at the rehabilitation facility, which was also where Kaeya had his therapy. Diluc read through all the policies and requirements for the out-patient program. When he was done, he went to check on Kaeya. Kaeya had been doing his school work when Diluc came in. "Do you need any help?" Kaeya only shook his head as he continued with his work. Diluc still went next to Kaeya and looked over his work. "Childe, Amber, and Albedo have been assisting me in notes and lessons. Speaking of which, Albedo is coming over later for a few. He's the one dropping off the notes and he's going to review with me. I figured you wouldn't mind." Diluc only nodded before putting down his brother's papers and taking a seat in a newly added second chair. "Have you looked over your treatment plan? You start the out-patient program tomorrow. From what I understand, it's like you're in a small class with some other kids that have mental health problems." Kaeya looked up to his brother "Yeah, I skimmed through the stuff." Diluc patted Kaeya's hair which only got a pout from the younger one. After an hour of helping Kaeya with his work, Albedo arrived and took over helping him with his schoolwork. Diluc went back to his own work seeing as he had to finalize the winery's paperwork. His schoolwork was already completed and he wasn't one to get behind.
When Albedo left, Diluc came up with his brother's antibiotics. "Kaeya, really?" Diluc said when his brother locked himself in the bathroom. "I will not be putting that nasty stuff in my body." Kaeya called out from behind the door. He didn't care that it was helping him. He only cared that it was grape flavored. He thought it tasted vile no matter what form it would take. The first time he had to take it, Diluc tricked him into taking it. He was stopped from spitting it out and instead swallowed it to get the nasty taste off of his tongue. The second time, Diluc somehow managed to get it to be a filling to a candy he gave him. This time, he wouldn't be able to get him to take it. Kaeya then flinched at hearing his brother essentially pound on the bathroom door. "Kaeya Alberich- Ragnvindr open this door now." Kaeya heard his brother say in a strong but calm voice. He knew that meant he was in trouble. So he naturally ignored his brother when about two minutes later his brother called him again. "You have until the count of three to open the door." Kaeya rolled his eyes as he sat on the floor and rolled his eyes. While we scrolled through his phone the door practically evaporated. A few wooden shards littered the bathroom door. He saw Diluc straighten up and look at him before the redhead grabbed his ear. "Ow, please let go! Diluc!" Kaeya cried as Diluc let go only to push him down into the office chair. After Diluc finished scolding him he attempted to have his brother take the medicine again. Kaeya decided that bolting would be the best choice as he ran out of Diluc's and his shared office- bedroom. Diluc let out a sigh as he chased after his brother. "Kaeya, I will take your phone away if you do not stop this instant!" After that Kaeya slid to a stop slightly glaring at Diluc. "That's enough. Go take the medicine." Kaeya stomped up the stairs with Diluc following him. Once they were back Diluc watched Kaeya take the medicine then glare at him. "Kaeya, it was all the pharmacy had. Please try to work with me here. I can talk to Adeline to see if she knows any other way to mask the flavor." Kaeya slumped a bit guiltily and nodded after a few moments. "Okay. Tomorrow you start your program so I want you to rest tonight."
In the morning, Diluc and Kaeya got up earlier than normal and followed with their morning routine. Once they ate their breakfast, they got into the car. Diluc dropped Kaeya off at the outpatient program meeting with those who were in charge of it learning the rules for dropping off and picking up Kaeya. Diluc was required to come in to collect and drop off his brother. After politely ending their conversation, Diluc hugged Kaeya and drove to school.
After Diluc left, Kaeya just slumped into one of the office chairs that was there for the patients who were participating. As he was swirling in his chair back and forth, a familiar face came in. "Why, I didn't expect to see you here!" Kaeya called out to a petite blonde who gave a small sad smile to him. "Hey Kaeya, your brother making you go through this too?" Lumine asked who only received a nod from Kaeya. "God, Diluc became even more overbearing. He's been watching me like a hawk, or having Elzer and Adeline babysit me. I know it's all 'cause he cares and wants the best for me but still." Kaeya let his head swing back over the computer chair after complaining about being under constant surveillance. "Xiao, Dain, and Aether have all been insufferable. I can barely use the bathroom without them needing to be around me to make sure I'm okay. Not only that, but they removed my door. My fucking door, Kaeya." Lumine vented to him until more kids filed in and took a seat in any random chairs. After a few moments, the mentors came in and began the sessions.
"Diluc! How are you doing?" A familiar voice called out. It was Aether and Diluc allowed himself to give a polite smile and nod to the boy. "I'm well, and you?" They could both see the bags under their eyes and the lines in their faces. They both knew about each other's siblings and knew the effect it had on them. "I'm well as well, how's Kaeya?" Diluc sighs "He's as good as he can be. What about Lumine?" Aether sighs "About the same." After that they both accompanied in a comfortable silence as they went to their homeroom. Soon, the day started and Diluc focused as much as he could on his studies. After a full day of studies for Diluc and a full day of therapy for Kaeya, both were a bit tired out. They didn't want to have to do anything else that day, just go to sleep and stay asleep. After a few days, they got used to the new routine. Soon a few days became a week, then two going on three and there was no change in Kaeya. Diluc didn't know what else to do and felt his brother seem to disconnect more and more, almost like he was fading away. Diluc was trying to keep his cool, trying not to panic but then something he didn't expect happened...