On Subjectivity

In philosophy, 

A Subject is a being that has:

Subjective Experiences

Subjective Consciousness 

or a relationship with another entity (Object)

A Subject is an Observer and an Object is a thing Observed. 

In critical theory and psychology,

Subjectivity is the actions or discourses that produce individuals or 'I'

—the 'I' is the Subject.

So, the Subject is both

that which Observes the Object 

and 

that which the Object acts upon (produces)

Georg Hegel defines this inherent tension, as pure negativity:
"...the bifurcation of the simple;
it is the doubling which sets up opposition,
and then again
the negation of this indifferent diversity and of its anti-thesis"

Which is to say,
The Subject is that which produces the Subject/Object Opposition
AND
The negation of this Opposition (by the nature of its being)

Or,
The Subject's Observance of the Object
at once
manifests the observable demarcation of Subject and Object
while negating this distinction in being acted upon by the Object

The Observance of the Object
(which we have called marking)
is the Subject being (momentarily) with an Object
which simultaneously acts upon the Subject

So while the Observance of the Object
manifests the observable demarcation of Subject and Object
(the awareness of Other-than-Subject is the coming-into-being of Other)
that demarcation is negated in the mutuality of Subject/Object relations

(the marking of the Object)

What manifests is an illusory division between Subject and Object

which obscures the Subjective marking of the Object

by denying this perpetual (yet momentary) symbiosis