C instances communicating with each other

gistfile1.js

"use strict";
var getInstance = (function(){
  var p = Object.create(null);

  return function(){
           return Object.create(p);
         };
})();

var c1 = getInstance();
var c2 = getInstance();

Object.getPrototypeOf(c1).c = 5;
console.log(c2.c); // 5