First appears in Donna Haraway "Companion Species Manifesto."
“The category companion species helps me refuse human exceptionalism without invoking posthumanism.”
"Dogs as the most significant example of companion species, the cyborg being but a toddler in our world of inter-species relations".
Cell phones, for example, could be considered a companion species. They cry, and must be picked up. They must be plugged into a wall at night to be fed. They must be upgraded, protected, and cared for. In return, they provide information, connectivity and entertainment. They grow alongside humans and adapt to fit their needs, as humans adapt to fit the needs of the device.
Also a great example of companion species are Pokemons: