When the great sage Nārada was glorifying the pastimes of the Lord with his vīṇā, the four Kumāras, headed by Sanaka, although merged in the impersonal conception of Brahman, were trembling all over. Another devotee once exclaimed, "Although I can achieve liberation simply by serving the devotees, my mind is still very much anxious to see the Supreme Personality of Godhead, whose bodily complexion is just like a dark cloud." When a devotee is so anxious to contact the Supreme Personality of Godhead, that can also be accepted as a symptom of neutral love.
Generally, a devotee of Lord Kṛṣṇa can be placed into one of three groups. One group consists of those who are completely dependent on the merciful affection of the Supreme Personality of Godhead; another group consists of devotees who are dealing with Kṛṣṇa on friendly terms; and the third group consists of those who are dealing with Kṛṣṇa as His superior, with parental affection. These three classes of devotees gradually develop different relationships of transcendental mellow with the Personality of Godhead. When the attraction for Kṛṣṇa is based only on one particular humor, that is called kevala, or pure state. One in this pure state of devotional service gradually develops the desire to follow in the footsteps of an eternal associate of Kṛṣṇa, e.g., to follow in the footsteps of Rasāla, the personal attendant of Kṛṣṇa in Goloka Vṛndāvana, or to follow Kṛṣṇa's friends, like Śrīdāmā and Sudāmā, or to follow Nanda and Yaśodā, devotees in parenthood. Ecstatic love for Kṛṣṇa is never manifested directly with Kṛṣṇa Himself. The devotee has to follow in the footsteps of the eternal associates of Kṛṣṇa in Goloka Vṛndāvana.
When transcendental humors in relationship with Kṛṣṇa become mixed (e.g., when the relationships with Kṛṣṇa in friendship, servitorship and parental love become mixed together), the result is called mixed humor or flavor. Such mixed transcendental flavors are manifested by such devotees as Uddhava, Bhīma and Mukharā, the personal attendant of Mother Yaśodā. Although devotional humors are sometimes found in mixtures, a particular humor is always found to be a prominent and constant factor. That prominent humor is to be accepted as the devotee's main relationship with Kṛṣṇa. For example, Uddhava is in relationship with Kṛṣṇa as a friend, but in Uddhava's character a trace of servitude to Kṛṣṇa is also visible. Such friendship is called friendship in reverence. The friendship typified by Śrīdāmā and Sudāmā, however, is the standard of friendship without any tinge of reverence.