LoJack
You could tell where Mystel slept because of how his hair smelled.
Tropical flowers, or subtly vanilla, or like mint, or like nothing, he'd been at the Siebalt's. He'd been using Kylie's, or Garland's, or Jamie's, or Brooklyn's shampoos. And his hair came out of the midst of their products looking particularly controlled.
Like nondescript drugstore soap or strawberry children's detangling shampoo, he'd been with Moses and Monica. And his hair came out looking either coarse or fluffy. And often in a multitude of braids tied with pink pom-pom rubber bands.
If Mystel's hair smelled like a berry smoothie, and was an extra-shiny version of usual, he'd been at Ming-Ming's. Like oranges, and normal-looking, he'd been with his parents. Like spice—any kind of spice—, wind-blown and sweaty and dusted with dirt, he'd been with the White Tigers.
When he was with all of them, he smelled like all of them. They joked half-irately that he conducted experiments in the bath, mixing their travel-sized shampoos into something smelling like a Grecian food and flower bazaar marinade. But Mystel knew what that smelled like, and disagreed, and joked how it was a favor to Garland. So Garland could keep up.