Scriptures and Rasika Vaishnavs mention about 5 rasas which only a fully liberated soul (jiva) when in complete awareness of their spiritual identity or eternal relationship with Divine Couple can serve Them in different bhavas. 

Contents   
1 to 5 Transcendental Rasas of a devotee for Krishna
1.1 Shant Rasa
1.2 Dasya Bhav
1.3 Sakhya Bhav
1.4 Vatsalya Bhav
1.5 Madhurya or Kanta Rasa

5 Transcendental Rasas of a devotee for Krishna

Shant Rasa

Here, the jiva takes a form which is not directly in reciprocation but in service of Divine Couple. For example, they become a throne, flowers, grass,  trees etc. to give pleasure to the Lordships during their asta-kaliya nitya lilas. However, there is not free exchange or reciprocation of love in full terms, hence once a sadhaka or devotee reaches this level and aspires for more, he can progress to next rasa.

Dasya Bhav

Here, the devotee offers service and bhakti to Lordships in awe, reverence and respect but there are formality and restriction of complete exchange of love. Even though, devotees whose constitutional position is dash bhav is highest for them. For example, Prahladha Maharaj Ji worships Narayan in Dashya Bhav and Krishna or Narayan takes the form of Narshima Dev to protect His devotee. Also, Hanuman Ji's servitude and surrender to Shri Sita Rama is worshipped time and again.

Sakhya Bhav

Devotees play with Krishna in the spirit of a dear sakha or friend. They eat food with him, steal curd, throw pebbles on gopis matka (pot), joke with him and freely exchange the bhav of friendship with Him. It is a beautiful state of expression of love, however, there is unavailability of freedom of full expression intimately.

Vatsalya Bhav

Here, the devotee is older and senior to Krishna and is in the mood of parents and sees Krishna as their little lalla or dear most child. There is a free flow of motherly, fatherly (or paternal love) for Krishna which is indeed beautiful, but yet there is a scope for a more free flow of love without any restrictions. 

Madhurya or Kanta Rasa

This is the topmost madhurya rasa where the devotee is Krishna's dear sakhis (female friends) and lovers. All the boundaries that were there in earlier 4 bhavas are crossed here. The flood gates of prema-rasa fully open in this bhav and the heart of devotee and Krishna is flooded with love. Here, the devotee does everything for satisfaction and pleasure for only and only Krishna. This is a confidential secret for very few and Srila Prabhupada has preached the Hare Krishna Mahamantra as given by Chaitanya Mahaprabhu, and the maha-mantra straight away gives access to this topmost madhurya rasa with due course of sincere chanting and having lalsa (desire) and lobha (greed) for vraja-prema-bhakti.