As you enter your room, you see Mark, changing his clothes, he looks really hot (wait what?!), and you expect him to be shocked, but instead he says "Miles are you okay? What happened to your pants bro?"
Miles?! Who the heck is Miles?
Then it hits you, you're a younger version of Mark, which is his brother. It makes total sense.
Then some memories of you and Mark spending a lot of time together, playing games, skating...
Mark says "Is that my t-shirt?"
Then you notice that you're still wearing a really large t-shirt (which is now probably Mark's) and no pants or boxers at all.
"It's... Nothing I'm just... Nothing" you say and go to your room.
After a few minutes of settling down, you begin to examine your new room. Your room is smaller than your old room. It is more colourful and childish, you see a skate at the corner, that explains all these muscles.
Then you decide to get dressed. You find boxers, a blue t-shirt and sweatpants.
Mark's (now yours too) mom comes and tells you that the dinner is ready. Your father asks you about your day, you tell him that you went skating with your brother after school, which you actually *did*.
After dinner you go to your room and play video games. It feels great to be this young, you don't have any homework or other responsibilities, and the next day is Saturday so you can just play video games.
After 30 minutes of video games, your new mom comes and tells you to go back. You protest in a bit too childish tone, but you're feeling sleepy so you just go to bed.