This is what will happen.
In a few years, I'll leave home, will rent a nice flat and will invite you in, with the excuse that that way I won't be alone and someone will look after for me for my parents and won't let me get drown in the bathtub or put my head in the oven. You won't be convinced, first, but then I'll tempt you with the idea of being away from your parents and sister, and you'll call my door next morning with your things packed.
We'll feel like strangers, maybe, the first days, and will make up some rules, so they'll be clear for both of us, but we'll laugh about them as we giggled about the laws of our invented country. Still, every morning, we'll fight because we will want the other to have shower first. We'll steal Internet from the neighboors, 'til we can pay some. Anyway, near the door of our apartment we'll hang a sign saying: "We teach Maths & Chemistry. We are explosives' makers too. If you don't get good marks, explosives will be for free"
I'll work and study 24/7 because, you know, being a Medicine student is actually pretty way of saying 'vampire' or 'zombie', so maybe you'll get angry with me because I won't be able to have lunch with you everyday.That's why I will leave post-notes everywhere, on your planes, your rules, pencilcases, maquettes, toothbrush and else. And you will do the same, and maybe I'll find a note on a patient's liver. The post-it's war will last a few weeks, or whenever we start using toilet paper.
I will hate the fact that our living room will have the smell of your cigarrettes, and will give you the lecture of what tobacco does to your system at least three times a day. And you'll have it memorized, but won't listen, anyway, or will just tell me to fuck off, or promise me it won't happen again, even if I know that it will.
We'll probably get drunk on weekends, watch stupid movies, our legs tangled, sitting on the couch with loads of ice-cream, and will complain about men, even though neither of us can really talk about such theme, but it doesn't matter: we'll say that they're useless and stuff. We'll maybe end up sleeping there, and wake up the next morning with a nice cup of tea, muffins and ibruprofen (because, you know, we'll never run out of ibuprofen, paracetamol and other analgesics).
You will hate the fact that I leave my clothes everywhere, my room will be a mess, with books and things everywhere, and will eat anything at any hour, except from some days, when I'll cook a so-called dinner for us, and we'll talk about everything and anything at all, and will build castles in the sky for one night. We'll have a toast for our future madness: house, dog, car, backyard (because we'll have it in case any of us has to bury a corpse there), study and surgery.
We'll have good wine and bad music, and from time to time, we will light up some candles, because the energy company will cut it out when I forget to pay the bills or when the city is at another of its beautiful summer energy crisis. The blackouts will be kinda fashionable, but you'll look after me, so I won't trip over delicate things and break them. Neighboors will hate us, because we'll sit on the window, and sing 'til our lungs and throats go dry.
And we will be happy, so happy together, and everyone will know it.
Happiness will last for a few months or years, if we're lucky. Until one of us get tired of the other, or meet somebody else, or fall in love with someone real. And then, I don't want to know what will happen...