These principles are easy to forget. We like our black-and-white narratives, with clear heroes and villains. The very term symbiosis has been twisted so that its original, neutral meaning – ‘living together’ – has been infused with positive spin, and almost flaky connotations of cooperation and blissful harmony. But evolution doesn’t work that way. It doesn’t necessarily favour cooperation, even if that’s in everyone’s interests. And it saddles even the most harmonious relationships with conflict. - https://aeon.co/essays/there-is-no-such-thing-as-a-good-or-a-bad-microbe