Girl with a hidden secret. Adrien/Chat Noir x Reader

Finally the end of the day.

Any texts or calls will be shown like this. "This." Just so it's easy to tell what's what.
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I headed out of the school and felt my phone buzz. I grabbed it out of my pocket and looked at the message.

"Hey lil sis. Your going to have to head home by yourself since me and (b/n) haven't finished school and work and dad has gone to the shops to get food so he can't pick you up as well. Be safe."
"Kay. Hope you are safe as well."

I put my headphones in and began to listen to on of my favourite songs before I began to make my way home. I made it about 20 steps before I was tapped on the shoulder making me jump. I turned around and took one of my headphones out looking at the culprit.
"Oh hey Adrien. What's up?"
"Hey (y/n). Wanna walk together?"
"Don't you have some after school class thing? Also are you sure we live close to one another?"
"Thankfully not today. And I saw you walking this morning with two other people near where I live."
"Oh they are my older siblings. My brother is a chief and my sister is going to university to become a vet tech."
"That's so interesting."
"You know you sound a lot like someone but I'm not sure who."
"Really? I wonder who it will be."
"I'm not sure. But if I could just hear their voice I can work out who."
While we were walking my phone buzzed again. I stopped and pulled it out to see it was a text from Alya.

"Hey girl. Just texting to make sure I'm in your contacts. Here's the clip of Ladybug and Chat noir like you asked."
"Thanks Alya. I'll see you tomorrow."

I put my phone back into my pocket and began to walk again.
"Who was that?"
"It was Alya. She sent me a Ladybug and Chat noir clip like I had asked for."
"How come you wanted that?"
"It was because of the first day I got here they helped me and I wanted to learn a bit more about them."
"Chat noir is pretty cool right."
"I wouldn't know. He seems really nice and caring though. He gave me back my necklace and I was so thankful for that."
"You see to really like the necklace."
"Oh yeah my mother gave it to me for my 15th birthday. My sister got one that looked alike and she had also wore one as well. So I no matter what she is always close to my heart."
"That's nice."
"Hey (y/n)! Shouldn't you be home by now?"
"Sorry I was walking with a friend."
"A boyfriend?"
"No just a friend (s/n)."
"Who's this (y/n)?"
"Oh this is my older sister (s/n). Sis this is Adrien."
"Oh your the famous kid right. I wouldn't stay out too late just in case your old man gets worried about you."
"I won't. I'll see you later (y/n)." He said before walking off.
"Bye."
"He seems like a good kid. Now come on we gotta get home."
"Yeah."
(I'm so close to figuring it out. Why his voice seems familiar.)