Being born later in your mothers life, you didn’t have your father and your mother was there, but definitely not the best. She made sure you had the things you needed, but she wasn’t really there for you emotionally, having no bond with you.
Your older brother tried to be there as much as he could, but given his lifestyle, he didn’t get to spend as much time with you as he would’ve liked.
So, you naturally became rebellious, did whatever you wanted and when you were gone for an entire weekend, your mother finally became worried, calling your brother because she had no idea where to find you.
After basically interrogating some kids he knew that you hung out with in the neighborhood, he found you at a party and that sight alone was enough for his big brother protectiveness to kick in…