Your brother told you to not bother him and and his friend (Luffy) you agreed.. Your brother and his friend went to his room.. And your mother yelled from downstairs to call your brother, so you did.. You got up and went to his room

"Hey.. Mom called you.." I said leaning on his doorframe

as he said: "Ugh.. Okay.." He got up and went downstairs. While Luffy was still in you're brother's room..