Stanley Calvins was a former Zero III of the elite Paxton family organization. He was one of the best Zero members due to his second to none programming abilities.
One of the digital program creations was Tiffany, which was destroyed when Katie's heart stopped beating within the allotted time limit.
After that incident, Stanley again tried to make a program that functions as a tracking device at Vincent's request, and he made it so that tracking machine devices could not detect it.
He inserted this tracking chip into Chleo's camellia bracelet. The girl knew nothing about the chip, but they would be able to track down Chleo and find out where the girl was if anything untoward happened.
Seeing that Chleo's carelessness was beyond help, they couldn't attach the program to the other accessory items. They knew Chleo would never lose her precious bracelet or take it off, so they purposely embedded the chip into her bracelet.
