Not sure if this counts as Yandere or maybe just an obsessed Sanzu? But here's a warning anyway.

     You and Sanzu were friends for as long as you could remember. You were always around Sanzu since you were kids. He was the only person you could felt like would care about you. He had his moments when he did scare you though, but you knew he would never hurt you. All he wanted was for you to be safe.

     But as time went on and you guys grew up it became harder for him to protect you. He got involved in serious and illegal things, while you lived as normal as one could. You'd always see him from time to time but it was never for very long. Either his boss needed him or he didn't want people to suspect who he was and get you in trouble. Today was different though.

"Are you sure about this Sanzu? We've never been out in public, mostly because you don't want us to."

"I'm sure. Just wear this and you'll be fine. I'm not gonna let anyone hurt you plus its dark out, and I'm in sweats, no one will even know its me." Sanzu said handing you a black mask, one like he used to wear when we were younger.

You slipped it on and out the door you both went. You couldn't lie, even though you were scared out of your mind it was nice to have Sanzu accompany you around for once. You both walked around town just enjoying the night life. Sanzu pulled you close as you walked pass a group of men. You clung onto his arm starting to feel nervous.

"I got you. I'm not gonna let anything happen (Y/N). I love you too much." Sanzu said.

     You could almost feel your heart break. This wasn't the first time Sanzu had admitted he loved you, you actually lost track of how many times he's said he's had feelings. You loved him, you really did, but you just couldn't bare the thought of what he did. You knew he was in a criminal organization and you knew he did bad things but he never went into detail, simply said you shouldn't worry about it. You pulled him to a park and sat down with him.

"The moonlight makes you look breathtaking (Y/N)." He spoke. "I could stare at you for hou-"

"What do you do in Bonten?" You asked cutting him off.

"What?"

"I want to know what Bonten does, and don't say I shouldn't worry about it." You persisted.

"You really shouldn't worry. Just know I do my job and no one complains." He smiled at you.

"But what if I WANT to know what you do? Is it that bad you can't tell me?"

"Listen (Y/N) like I've told you a million times already, you really shouldn't worry about it. What I do and our relationship have nothing to do with each other okay?"

"I know but- wait, what relationship?"

"Oh you know." Sanzu said smiling at you but this smile seemed different.

You stared at him and his smile. The more you stared the more uneasy you felt.

"No Sanzu, I don't know. What relationship between us are you talking about? We don't even have a relationship."

Sanzu's smile dropped as you said there is no relationship between the both of you.

"Come on Sanzu, I've told you before I love you, but not like that. You'll always have a place in my heart but we're just friends." You spoke softly knowing this was touchy for Sanzu.

"What can I do?" Sanzu asked you as he looked at the table.

"Huh?"

"Is it something I did, or didn't do? I can change I can- I can change for you I will. I promise." Sanzu carried on.

This reaction took you by surprise. Sanzu would usually get upset but never to this extent of almost a panic-like reaction. Had you gone too far with saying theres no relationship? But you weren't wrong you guys have a friendship, not a relationship. You were in thought and almost forgot Sanzu was still carrying on.

"Please (Y/N) I love you! Please just give me a chance I'll do whatever you want just please."

"SANZU!" You screamed so he would stop talking. "You shouldn't change for someone to love you. You'll meet someone someday who you won't need to change for." You smiled at him holding his hands.

"But... I wouldn't mind changing if it was for you." He whispered.

You and Sanzu sat in silence for a few minutes before you decided it was time to go home. Sanzu walked you home and was about to leave before you called out to him.

"Sanzu. Don't go, come inside for a bit." You offered and Sanzu walked right into your apartment.

You and him sat down at your coffee table. There was an awkward silence. Sanzu didn't speak and you weren't sure if you wanted to speak, but eventually you did.

"Do you want something to drink? Water, juice, wine?"

"Wine." He responded.

     You nodded your head and got up grabbing two glasses, a bottle of wine, and a bottle opener. You sat down across from him and placed everything down on the table. Sanzu got right to work opening the wine bottle. He poured about half a glass into yours and nearly filled his glass to the top. Sanzu picked up the glass and tapped it against yours before drinking almost the entire glass in one go.

You sipped on your glass and soon both of you needed more wine.

"Hey Sanzu, could you pour me a little more? I'll be right back." He nodded his head and took your glass.

     You stood up and made your way into the bathroom. You didn't have to go, you simply had to dry your face of the tears that rolled down your cheeks. You knew the tears were because of Sanzu. You really did love him, but you weren't IN love with him. He really did have a special place in your heart but you figured thats where he was gonna stay.

Once you had collected yourself you flushed the toilet and washed your hands before turning off the light and going back to the living room. You sat down across from Sanzu again before he spoke.

"You didn't actually use the bathroom."

"W-what?"

"I saw the tears even before you got up. I don't mean to make you sad (Y/N)." Sanzu said with his head down. "Maybe I should just-"

"NO!" You yelled. "Please don't go. I don't want you to leave me here alone." You cried.

You scooted next to Sanzu and grabbed his hand.

"You're my best friend and I would do anything for you. I love you Sanzu, I really do, I'm just not in love like someone should be." You spoke truthfully. "I will always care about you. Please don't end our friendship over this."

Sanzu was quiet before he wiped the tears from your face.

"I just figured you'd be better off without me."

"No I'd be lost if I could never see you again."

"Okay. I'm sorry." He said.

"Don't be sorry, you can't help what you feel."

You and Sanzu sat next to each other before he passed you your glass of wine.

"Don't waste it. This is a good year." He joked looking at the year printed on the bottle label.

     You drank down the wine in no time. You guys had continued to talk for a little while longer before you started to feel ill. Sanzu felt your head hit his shoulder before sliding down his arm. He smiled to himself before picking your head up. He laughed at your clear unconscious state before picking you up.

He brought you to your bedroom and laid you down on the bed. He took out his phone and walked out of your room before calling someone.

"Yeah, boss. I'm not gonna make it back tonight. Yeah I'm caught up with my girlfriend again but don't worry I'll be back bright and early tomorrow morning. Okay, sorry for the inconvenience, goodnight." He said hanging up the phone.

     He walked back into your room shutting the door behind him. He maneuvered the blankets so you were underneath them before he laid down in the bed as well. He pulled the covers over the both of you and pulled you into his body, wrapping his arm around you. He took in a deep breath before relaxing into the bed with you.

"You feel so perfect in my arms. I just want to keep you here." He spoke to himself. "You will be mine one day (Y/N) either by choice or by force, but you will be mine." He whispered.

The next morning came and you woke up in your bed. Your head felt like it had been put through several brick walls. You stood up and wandered around your house seeing a note on your kitchen counter.

(Y/N) I guess you had a little too much to drink last night because you passed out out of nowhere. Maybe I shouldn't have poured you so much wine haha. Theres some painkillers and water on the table. Rest up and I'll see you around. <3 Sanzu

"I only had two glasses though." You said to yourself. "How did I pass out?"