IF - Introverted Feeling

Introverted Feeling (Fi) is:

• A Subjective, Rational, Feeling cognitive function.
• Introverted Feeling seeks to judge the value of objects based on subjective factors, while completely suppressing the influence of the object. That means assigning value to objects purely based on the subject's sentimental standards. Fi seeks to stay in full alignment and influence of it's subjective values.

Introverted Feeling (Fi) explained from MBTI authors:

Is determined chiefly by the subjective factor and serves as a guide to the emotional acceptance of rejection of various aspects of life.

Adapts the objective situation to the individual by the simple process of excluding or ignoring the unacceptable.

Depends upon abstract feeling—ideals such as love, patriotism, religion, and loyalty, and is deep and passionate rather than extensive.

Finds soundness and value inside one's self from one's own inner wealth and powers of appreciation and abstraction.

Has as its goal the fostering and protection of an intense inner emotional life, and, so far as possible, the outer fulfillment and realization of the inner ideal.

May be too overpowering to be expressed at all, creating a false appearance of coldness to the point of indifference, and may be completely misunderstood.

Has a tendency to find no objective fulfillment or realization—or outlet—for expression, and presents the danger of living upon sentiment, illusion, and self-pity.

Myers, "Gifts Differing: Understanding Personality Type"

Introverted Feeling (Fi) explores and refines personal tastes and feelings, contributing to a strong sense of personal uniqueness. It is self-regulating and self-controlling, working to maintain inner emotional and moral order.
It may also emotionally invest in a limited number of love objects, be they persons, animals, hobbies, or causes.

A.J. Drenth, "My True Type: Clarifying Your Personality Type, Preferences & Functions"

Quester Fi:

Pursue a singular life quest or truth. Aim for moral clarity. Dedicated to congruent set of beliefs. Align quest and core personal identity. Listen to a select voice like one's own conscience. Contain your feelings

Romantic Fi: 

Live a life of deep quiet feeling. Listen to and harmonize with many voices. Pursue multiple soft quests. Allow room for inner and outer conflicts. Identity is subtle, diffuse, and varies in context of each relationship. 

Dario Nardi, The Magic Diamond: Jung's 8 Paths For Self-Coaching