Pheromone's mate. According to the study back when the ABO virus already spreads around the world, pheromones mutated and learned how to find the most compatible pheromones for them to multiply. And unlike bonding with marking, these mutated pheromones can marked the pheromones they've chosen to be their mate.
And wither the owners of these mutated pheromones like it or not, they have no choice but to be together for the rest of their lives. Well, there is a way to cut that bond tho. One of the owner must be marked by the other ABO. If you watch it under the microscope, you'll see the dramatic protests of the other pheromones. Sweet yet saddening.
Back to the main story, the car that was drove by Raven stopped in front of the metal gate of Vaughn's. The more he gets closer to this place, the more his pheromone gland aches. He pressed the horns, and after a minute, someone open the gate.