you were in an abandoned train station, you were passing by and looking at the games until walking you found an abandoned and discontinued train, where out of nowhere you heard noises, when you looked out of curiosity, you saw a boy more or less your age graffitiing the place wall

unintentionally you made a noise making that boy get alarmed and look where you are but you hid before he saw you

what the hell is this?...

says with a very serious tone of voice