John D. Zizioulas

“The person is otherness in communion and communion in otherness. The person is an identity that emerges through relationship; it is an 'I' that can exist only as long as it relates to a 'thou' which affirms it's existence and it's otherness. If we isolate the 'I' from the 'thou' we lose not only it's otherness but also it's very being; it simply cannot be without the other.
Personhood is freedom. In its anthropological significance, personhood is inconceivable without freedom; it is the freedom of being other. I hesitate to say 'different' instead of 'other', because 'different' can be understood in the sense of qualities (clever, beautiful, etc.), which is not what the person is about. Person implies not simply the freedom to have qualities, but mainly the freedom simply to be yourself.
And yet because, as we have already observed, one person is no person, this freedom is not freedom *from* the other but freedom *for* the other. Freedom thus becomes identical with *love*. We can love only if we are persons, that is, if we allow the other to be truly other, and yet to be in communion with us. If we love the other not only in spite of his of her being different from us but *because* he or she is different from us, or rather *other* than ourselves, we live in freedom as love and in love as freedom .
[In this way] personhood is creativity. Freedom is not *from* but *for* someone or something other than ourselves. This makes the person *ec-static*, that is, going outside and beyond the boundaries of the 'self'. But this *ecstasis* is not to be understood as a movement towards the unknown and the infinite [an arbitrary, abstract *othering* for the sake of itself]; it is a movement of *affirmation of the other*.
This drive of personhood towards the affirmation of the other is so strong that it is not limited to the 'other' that already exists, but wants to affirm an 'other' which is [the product of] the totally free grace of the person. The person [out of totally free grace] wants to create its own 'other'. This is what happens in art; and it is only the person that can be an artist in the true sense, that is, a creator that brings about a totally other identity as an act of freedom and communion.
The subject of otherness, then, is raised in its absolute ontological significance. Otherness is not secondary to unity; it is primary and constitutive of the very idea of being. Respect for otherness is a matter not [only] of ethics but of ontology: if otherness disappears, beings simply cease to be. There is simply no room for ontological totalitarianism. All communion must involve otherness as a primary and constitutive ingredient. It is this that makes freedom part of the notion of being. Freedom is not simply 'freedom of will'; it is the freedom to be other in an absolute ontological sense.”
― John D. Zizioulas, Being as Communion: Studies in Personhood and the Church