In school, Rosalyn was in the library with Brandon and Yuni. Rosalyn was stealing glances at Yuni all the time when she was reading her computer science book, where Yuni and Brandon were studying physics together. Brandon caught the sight of how Rosalyn was peeking at Yuni from time to time.
He didn't know why but felt jealous. He didn't like the way Rosalyn was looking at Yuni.
Brandon couldn't stop himself before he said out in a dry tone to Rosalyn with a cold glare, "Straight,"
The inner meaning is, Yuni is straight. So, back off.
Rosalyn got startled. She looked at him with a shocking expression on her face. Soon that turned into an amused smile when she said, "Into or over? I think it is into," She gave him a wicked grin.
The inner meaning is, Are you in love with her or not? I
