Aina stared at the whiteboard. Mr. Rahman had just written a complex redox reaction for their Kimia Tingkatan 4 class. To everyone else, it was a terrifying jungle of ions and oxidation numbers. But to Aina, it was a puzzle.

Aina smiled. Finally, an equation that balanced perfectly.

"Because in chemistry," Aina smiled, "when you add the right catalyst, even a broken reaction can start again."

"Friendship formula: Aina + Lia → Strong bond. No catalyst needed."

Aina knew the handwriting. It was Lia's. The next day, before the quiz, Aina walked to Lia’s desk. She placed the crumpled paper between them.