The immune system is commonly perceived as an army of organs, tissues, cells, and molecules that protect from disease by eliminating pathogens. However, as in human society, a clear definition of good and evil might be sometimes difficult to achieve. Not only do we live in contact with a multitude of microbes, but we also live with billions of symbionts that span all the shades from mutualists to potential killers. Together, we compose a superorganism that is capable of optimal living. In that context, the immune system is not a killer, but rather a force that shapes homeostasis within the superorganism.