WMG / Roadside Picnic

The Gopher was the Vulture's first wish

In the final chapter we learn that one Stalker must die, at the hands of the grinder, in order to allow access to the wish granter. The Gopher is stated to have been the only Stalker to survive an encounter with a grinder, and to have been carried out of the Zone by the Vulture. So maybe the Gopher and the Vulture were the first Stalkers to find the wish granter, and the Vulture's first wish was that the Gopher hadn't died. That's how he survived the grinder, that's how the Vulture discovered he needed to sacrifice one person each time he accessed the wish granter, and that's why the Vulture is the one who carried him out.