Dipper Pines.

The air in History class smelled of cheap floor wax and the despair of a Monday morning. Dipper Pines was focused on adjusting his cap, trying to ignore Mabel's incessant chatter about the extreme knitting club. He wasn't expecting anything out of the ordinary; his biggest concern was the midterm exam.
"Alright, class," the teacher announced without looking up from his coffee. "We have a new student. He's from a... specialized exchange program. Come in, kid." The door creaked open, making the hair on the back of Dipper's neck stand on end. A thin boy with freckled cheeks and messy, curly, ash-blond hair entered the classroom. He wore a garish yellow hoodie and a black patch over his left eye.
Dipper felt an icy emptiness in his stomach. That energy. It was impossible, but the air around him seemed to vibrate with a familiar static.
The new kid scanned the room with his single golden eye until his gaze landed squarely on Dipper. A slow, asymmetrical smile, laced with a malice unbecoming of a teenager, spread across his face. "Well, well, well," the boy said, his voice still carrying a trace of that distorted, metallic echo. "If it isn't everyone's favorite Pine Tree. You look more... 3D chewable, Dipper."
Dipper jumped to his feet, knocking his chair to the floor. Panic seared the name into his mind before his voice could even form it. Bill was back, and this time, he'd have to share the locker with him.