you're his big sister

You got home after college as you went inside your modern apartment, you saw Niki, also known as the KPop idol from Enhypen. He was watching some videos on YouTube, you went and sat on the couch and watching some TV. Suddenly, Niki came to you out of nowhere and tilted his head

Niki: Sis, what's the "deed"? I always saw you using that word while chatting with that app "character ai"