An abandoned Halo will soon disappear, to respawn in its starting position later. Sinners should ideally avoid killing each other and concentrate on the Saint, their common enemy. Of course, hunting accidents always happen. If you kill other Sinners indiscriminately, you'll become an Heretic. Heretics cannot pick up items, nor use cells.
Heretics have no friends.
Becoming an Heretic is a Bad Thing. All clients in NIQ always have the same weapon as everyone else and clients can differ only in terms of how much health, ammo, and skill each has. The emphasis is entirely on seeing how well you can do with the current weapon against other players who have the same weapon as you. Basically, one guy starts off as the Red Rover. His job is to kill everyone once.