Cross-posted on AO3

Day 1: Mind Control

Diluc knew that something was going on with Kaeya.

The Calvary Captain has been uncharacteristically quiet and hadn't really spoken unless he was spoken to. He didn't even make any of his usual flirtatious remarks, hadn't teased anyone, made any of his usual snide jabs at Diluc, nothing.

It was making him seriously uncomfortable.

But what had really made him realize that something was going on was when Kaeya even ignored Klee, the cute little Spark Knight with who he constantly got into mischief. He had taken the girl under his wing and had been teaching her many things, though most were how to get away with acting naughty. However, that had recently changed to the poor girl being down in the dumps since her requests to play were now being met with stony silence and a blank face.

That was when Diluc decided that it was time for him to step in and do something. There was no way he could let this keep going on any longer and he resolved to confront Kaeya the next time they saw each other.

That next time wound up being sooner than he had thought when he found Kaeya while doing his 'nightly duties.' The man was stumbling through the streets like a zombie, shuffling almost slowly and never looking around him to see if anyone was close by or watching him. It was a very unnerving sight.

He was quick to follow him into an alleyway and grabbed his arm, pulling him around to face him. The second he could see the man up close, Diluc finally noticed that he had missed something that should have been very obvious and that he couldn't believe he had missed.

Kaeya's eye was clouded over and he didn't even look directly at him, almost like he couldn't even see him at all. His breathing was also irregular, but heavy like he couldn't quite get enough air. While the man's state had caught him off guard, he also knew that Kaeya needed help and that he needed it last week.

Gently taking hold of his wrist, the tavern master carefully led the knight out of the alley and towards the cathedral. Maybe Barbara could do something to flush out whatever was in his system. It took a while to get there, Kaeya stumbling a few times and having trouble with the stairs, but he was careful not to let him fall. Thankfully, they made it to the cathedral without an incident, though exhaustion was making the younger move slower. Who even knew how long it had probably been since he slept?

Diluc was quick to slam the doors open as he ushered Kaeya inside.

"Barbara?! Is Sister Barbara here?!" he called out frantically. He knew that every minute could mean worse effects that could happen to Kaeya. Thank the Archons that Barbara had been awake and still in the main chamber. The girl was quick to rush over and immediately at their side, grabbing Kaeya's other arm to steady him.

"Oh, my goodness! What happened?" she asked, clearly startled by the late-night visit as well as the captain's condition.

"I think there may be some kind of drug in his system. He's completely out of it and there's something wrong with his eye and his breathing," Diluc was quick to say. The Deaconess's eyes seemed to grow larger as his explanation went on until she was ushering them to her office since it was closer than the sickbay.

The two settled Kaeya down on the couch, letting him lay down and rest. Barbara is quick to get to work and start checking Kaeya over, Diluc watching silently from behind. After a moment, she gave a sigh as she rose back to her feet and turned to the wine tycoon.

"Well, what I can tell you is that it certainly isn't a drug. It appears to be spell akin to mind control, probably just something used to scramble his mind and confuse him."

Any relief that Diluc had felt was quickly swiped away.

"What do you mean?"

"It's just -," she hesitated, before taking a quick calming breath and continuing. "Sir Kaeya was sent out to deal with a group of Abyss Mages." The young woman paused, looking troubled. "They must have done something to him then, but he looked completely normal when he came back." She truly looked distressed, frustrated how Kaeya could have gotten so bad and nobody noticed. "We don't know where the Abyss Mages are, so it's not like we can force them to remove it. Maybe we could get Mona to come and break the curse."

Diluc's face had already gone completely blank and Barbara could practically feel the temperature in the room rise. Without saying a word, the man turned his back towards her, summoning his claymore as he walked purposefully towards the door.

"Diluc? Wait! Where are you going?!"

He ignored the girl's calls as he continued to walk away. He knew that she wouldn't come after him, too concerned for Kaeya's well-being to just leave him there. But Diluc knew that it wasn't a one hundred percent guarantee that Mona would be able to help, so the next logical step would be to find and interrogate an Abyss Mage. Right?

Right.

He was just about to walk out the door when the sound of a softer, deeper, and very much male voice called out to him.

"Luc…?"

Spinning his body halfway back around, he was met with the sight of Kaeya still laying on the couch, but his arm was now reaching out in his direction. His eye was still looking around as if he couldn't pinpoint where Diluc was, but his fingers kept flexing as if trying to grab him.

As if begging him not to leave.

With a sigh, the redhead made his way back over. Kneeling by his brother's side, he gently took his hand while he rested his forehead against the other's.

"I promise, Kae, that I'll be right back. Okay? Can you wait for me until then?"

Kaeya made a weak whimpering noise but nodded his head as if they were still twelve years old and Diluc had been comforting him during a particularly bad storm. Rising from his crouched position, he turned to Barbara.

"Please keep an eye on him for me?"

The young lady gave him a nod, her earlier apprehension gone as determination took its place.

Diluc walked out the door.

A/N: The draft for this story was originally written on the 25th of January soon after I saw the prompts for this month. I actually did all of the prompts for days one through ten, including the alternate prompts. I still have to do day eleven through twenty-eight.

I'll try to have the alternate prompt for today up as well before bedtime, hopefully.