I said yesterday that even my fictional characters, even the mean ones, are me – and that is true, but at the same time, as a self you always react to an other.
Even if there has been some catastrophe and you find yourself alone in a high tower with no one for company, there will be an other somewhere.
Maybe you are Rapunzel and the witch will appear on a regular basis with your sustenance – the witch will be your other.
Maybe you see no one, and your food appears in pellets from a container (you are in hamster-mode), whose switch you need to press to get things working – and your drink caught in your mouth from an ever-flowing fountain –
There may still be a mirror in your room – your reflection is your other. You visit yourself often.
You talk to your reflection in the mirror – you get approval, mostly – unless a darkening cloud passes over the seals of your windows, its blackness permeating despite the hard clasps keeping your blinds shut, and changing what you see in the mirror, distorting it – altering what it appears to have been saying – everything different now.