Post-it Notes [JohnLock university au]

The Scarlet Thread

I sat up and saw a tall, tanned man with brownish grey hair walking in and slamming the door against the wall loudly. My roommates eyes darted with a narked off expression to the stranger who began speaking quickly.
"Sherlock-" " Lestrade if it's another obnoxiously boring case, leave. " my dark haired roommate (who was apparently called Sherlock) interrupted bluntly. He said something about a case, maybe he lost a suitcase or something?
"Nahhh Sher, I think you're gonna wanna see this"
Lestrade said, giving Sherlock a piece of paper with a lot of writing on it. I looked over curiously and Sherlock's eyes were flicking around the paper frantically.
Okay so not a suitcase, maybe he was like some sort of private detective or something? He must only be about 18 or 19 so I don't think he's old enough.
Sherlock rolled his eyes and spoke "I'll speak to you about it later Lestrade, right now I'm busy"
"busy doing what?" Lestrade asked sounding dumbfounded
"Thinking."
Lestrade tried to interject "Sherlo-"
"Leave now."
The taller man looked like he wanted to argue but shut his mouth and walked out.

"You look confused." The low voice hummed from across the room. at first I didn't know if he was actually talking to me or himself, but he was looking very intently at me.
"Well some random bloke wanders into my flat and starts going on about a case. Bit mysterious so of course I'd be confused. Anyway, I thought you'd said we weren't gonna be speaking to each other?"
" Lestrade. He's on the student watch, heard of it? Probably not they keep pretty low profile. Think themselves some kind of uni police. Bad things go on here more often than you'd think, they take care of it and I take care of whatever they're too dimwitted to solve if I don't find it ridiculously dull. As for us not talking, I'm bored and you've got an alcoholic sibling and a dead father. Continue." He rattled off quickly.
"How did you even...?"
"Simple deduction john" . I was really intrigued now "care to elaborate?" I questioned, wanting to know how on earth he knew about Harry and my dad and what he meant exactly by deduction.
"Your watch,discontinued model, clearly old suggested by the slight rust on the buckle so obviously passed down from an older generation. You have a picture of your father in an army uniform and a more recent photo of someone who looks to be your mother wearing a wedding ring on a chain. Your father isn't in the more recent photo and widows often keep their spouses wedding ring on chains so fair to assume he died given that the ring is larger than her finger.
   Things within families are typically passed down to the eldest          and since the watch has a small H scraped into it, fairly recent by the looks of it, the sibling had the initial H.
Now how did I know they're an alcoholic?
Everything your father wears in the photo is pristine, clearly implying he was a careful man and thus would have been careful with an expensive watch recently bought at the time. The scrapes on the bottom of the watch face are from some kind of desk given the pattern so either your sibling is a writer or is in bars and cafés a lot. Given the wide diagonal scrapes in the leather strap, right hand was often used to keep them upright, frequency of the scrapes suggest that was a regular pattern. Alcoholic."

Now, I was utterly dumbfounded. Tiny little details and he was 100% right about things some of my closest friends don't even know. No idea how he did it.
" brilliant! Absolutely brilliant" I spouted, not realising I'd spoken out loud. For a split-second Sherlock's eyes widened slightly before returning to their usual unfazed and distant glare.
"That's not what people normally say" he spoke calmly
"well what do they normally say?" I questioned
His mouth twitched up slightly "piss off"
I chuckled lightly then he joined in and we were both sat laughing like idiots for about a minute or two. I sighed deeply catching my breath before remembering something, " oh wait Sherlock, how did you know my name?" I asked quizzically
He pointed down to the empty suitcase I left on the floor when I flopped onto my bed earlier, the outside had a sticker reading "property of John H. Watson" he probably read it when I was at the door. "Ahhhhh makes sense"
A small text ding came from Sherlock's phone on the side table, he picked it up, glanced at it blankly before putting on a long trench coat and scarf and leaving abruptly.

I didn't remember falling asleep till I woke up, it was about six or seven o'clock. Sherlock was back after whatever he had to do and was rapidly writing on a post-it. can't say I wasn't curious but I didn't want to disturb him. I instead opted to read over some pages in my biology study book, no doubt I'd need some prep before classes. I heard the sound of a pen being put on the side table, movement and then a long held sigh. I looked to the wall, new post-it note with "Room locked, hard drive missing, envelope, red ribbon. Message: 'don't leave important documents unattended' left handed."
Curiosity was killing me at that point and I was willing to bet that post-it had something to do with that case thing.
My staring was met with a really harsh glare from the taller bloke sprawled on his bed. I took my eyes off the wall, feeling like I'd invaded the guy's privacy or something. Could still feel him staring again and I was getting a bit uncomfortable with the silence so I spoke "you alright Sherlock?"
" why wouldn't I be?" He replied, "I dunno, you seem pretty spaced out" he just mumbled something about needing to head out then left the flat without his coat.
A minute later I looked out of the window to see him talking to someone, the person left then Sherlock pulled a cigarette out of his pocket and started to smoke.

Once again, I glanced towards the huge spread of post-it notes.
There was stuff about something called Mycroft, sounded like some kind of computer system or a board game. random dates that had very little meaning to me, a ton of random unrelated words, mori-something, missing property and a ton of jumbled letters and a reminder to grab a new lighter.
My roommate was getting stranger and stranger by the day honestly, I'd like to know what all of this means but I didn't want to intrude. I'd decided to as him at some point in the future and had an early night.