All these things below could.
Some are quite possible, some less; some are invented, some actually happened.
Once you are gone...
... your brother will try to make his own pen. He will test each model by painting the pavement with your black ink. He will take your favourite black one, not the blue one. He will do this before you are really gone, giving you a chance to see the drying ink just as you are leaving.
... the crayons you had been given for Christmas and hardly dared to touch will be found by your small sister.
While you are gone...
... your sister will use your favourite T-shirt instead pyjamas.
... your mum escapes the crowded living room and uses your room as her study.
... the cat will be sleeping on your pillow and there will be fur everywhere.
When you return...
... you'll find out that you can't find anything. There are three possible reasons for this.
- It was ''borrowed'' by your siblings and you are never going to find everything again. An exception is your notebook. It is too obsolete to be of any interest to your brothers. They have got a newer one anyway. Another exception is the nintendo. Your mother once got desperate and borrowed it to one of your brothers who had managed to get his lost. You haven't seen it ever since.
- Your carefully maintained ordered chaos was replaced with something completely unmanageable and it will take you ages to get everything under control again.
- Even worse, your mum tried to tidy up.
... if that’s the case, you'll find that somebody went through your pile of important, semi-important and completely useless papers, sorting them and leaving only the trivial.
... you'll find dust under your bed. A lot of it. Don't worry, that's completely normal. If it starts crawling again, use the vacuum cleaner.
... you'll find socks under your bed too. That's because the clothes basket is right next to your door and everybody keeps throwing these socks (and occasionally missing).
... you'll find that nobody watered your plants. That's kind of logical, since you haven’t got any, since you have never watered them and they were long ago taken away from you.
... the chocolate bars you have been carefully saving will be missing completely. You'll never find any clues, and though you'll have your suspects you'll never be able to prove anything.
... you'll find your chair replaced by another of your younger brother's innovations. You won't be able to get it out of your room because
- There are so many nails in the wood that the floor directly underneath is bent.
- It looks like he assembled it in your room.
... the old alarm clock you were so sad when it stopped working will be thoroughly shaken by your brother and in the likely case that you find out, you won't be able do anything about it because it miraculously started working again.