Grrl Power/WMG

That thing Sydney can't be separated from contains...

 * ...an extremely persistent GPS.
 * ...GreenRocks
 * ...nothing; Syd's just psychic and delusional.
 * Or alternatively, psychic and messing with them for the lulz.
 * ...Sydney's Tardis.
 * ...a Cosmic Keystone.
 * ...GreyGoo
 * ...something else that'll cause The End of the World as We Know It if released.
 * ...bees and snakes/pokemon and ponies/cthulhu. Because no one is expecting it.
 * ...her Soul Jar.

Brook will be dead by the end of the prologue.
The only female hero - the only female character, almost - not to be on any version of the banner, despite apparently being an equal member of the team currently, and not seen in any of the earliest ads. Plus, the only one of the girls yet seen to have a partner. So doomed.
 * Prolog's done, nobody died. Jossed.