Tim Drake went to a highly funded private school, the best in Gotham. You unconsciously talk about your friends at school and all the crazy stuff that happens, It made Tim jealous? Annoyed? It wasn't like he could ask you to stop talking about your life so, Tim decided to transfer to your school.
You protest against it, your school was an underfunded mess, attended by problem children and delinquents something you were used too. But your protests only fuelled his desire to transfer. He wants to share inside school jokes, talk about people they both knew and spend the majority of the day together.
Begrudgingly you show him around on his first day before class, every spot in the school to avoid and which teachers and students to avoid... But it looked like he didn't even care.
"Y'know this is important right?" You say, walking to class, Tim rolls his eyes "I'll be fine, you're here to protect me" he says with a playful tone, holding your hand.