What happens is, a bike with a passenger crashes in some rural spot, paramedics arrive and find a rider who is dead, unconscious or otherwise not making a lot of sense. They roll away with their casualty and miss the pillion passenger, who is out of sight somewhere, behind some country furniture. Apparently several women have died this way in recent years, their corpses often not found for months.
Kathy recommends that both riders wear a dog-tag or med-alert necklace when riding two-up, to alert paramedics to the other rider. Paramedics always check for a med-alert bracelet or neck-tag. You can buy them in any pharmacy. Wouldn't do any harm to include the other person's cellphone which might help find the missing rider. Wearing some high-vis or autoreflective material might help too.
In a pinch, both riders could set each other up as the cellphone ICE contact for the other. Paramedics might make a triage mistake this way, and treat a less-injured person first, but the phone ringing might help find the other person.
Bikesafer.com is focused on avoiding accidents rather than responding to them, but we encourage all bikers to take MAST training, because any of our fellow riders might some day need our help. We should also encourage paramedic and firemen friends to take MAST training, where available, as part of their continuing education. Bike casualties are specialized and MAST-trained paramedics do a better job of saving biker lives.
That said, training and skills practice is what helps bikers avoid crashes in the first place.