Shloka 2. Bhagavad Gita 4:11:
In whatever way one worships me, I honor him in that same way, for in all their various ways men do follow my path, Partha.
19 [Saying] ‘My son, my friend, the lord of my heart’–he who has pure bhakti toward me in these bhavas, 20 who feels himself superior, equal, or inferior to me, I am dependent upon those in all these bhavas.
Shloka 3. Bhagavata Purana 10.82.44:
Bhakti alone to me leads to immortality for all beings. It is most fortunate that love toward me has been born in you, gaining my self.
21 Those who bind themselves to me as mothers, as if I were their son, and in knowledge of my dependency bring me up with care and protect me, 22 or as friends in pure friendship raise me up onto their shoulders and say, ‘You are no great one. You are the same as I,’ 23 or as lover, though they reproach and blame me, steal my mind away from those who sing the praise of the Vedas; 24 it is for the sake of these pure bhaktas that I have descended, and it is for their sake that I shall perform all kinds of wonderful activities.
38 Dasya, sakhya, vatsalya, and shringara–there are four bhavas, receptacles of the four types of bhaktas, 39 and each [bhakta] considers that his own bhava is the best of all; in his own bhava he tastes the happiness of Krishna. 40 But when, being impartial, one judges the bhavas, he finds that in shringara lies the greatest sweetness of all rasas. (CC 1.4)
Krishna Das quotes Bhagavad Gita 4:11 repeatedly to emphasize how free devotion to Radha-Krishna is. They’ll go along with whatever we want to do. They like when devotees treat them as an equals or even inferiors. Braj devotees forget that Radha-Krishna are God-dess. When we follow their examples and develop intense longing to enter their play as one of them, we will surely be successful.
Servanthood, friendship, elder, and lover are the four moods devotees manifest in Braj, and each thinks their own mood is best because that’s where they taste Krishna’s happiness. This is a subjective process. However, when examined objectively, amorous love is best since it includes the others as well as its own unique sweetness that surpasses them all. This is Krishna Das’ conclusion, and Chaitanya’s followers generally accept it.
Thus there is a profusion of literature dealing with the amorous relationship, but little on the others that I can refer people to who want to be in servant, friend, or elder relationship with Radha-Krishna. You can use the model I provide in my book for developing the amorous relationship but adjust accordingly. It’s best to find a role model from the literature such as Subal, Sridham, or Sudham if you want to be a friend, or become an assistant to Nand, Yashoda, or Kirtida if you want to be an elder. Then from the literature put together a storyline for the day as you see yourself involved with the play. It’s kind of like rewriting Romeo and Juliet as West Side Story.
One book I can recommend that is not in my bibliography is Jaiva-Dharma by Bhaktivinode Thakur. Although written as a novel, it is a difficult read due to being packed with technical theological language and ideas. It gives an excellent description of the siddha pranali and ekadash bhav process as it was practiced shortly after Chaitanya’s disappearance. One character is in amorous relationship and another is a friend. They are related and learn this process together.