The question is: “Is Bhakti something dormant / forgotten in our souls, and we have to wake it up / remember it by sādhana?”
The question arises in connection to Bhakti Rasāmṛta Sindhu’s definition of sādhana-bhakti not as a means to create perfection, but to manifest something eternally perfect. The question is also related to Bhakti Rasāmṛta Sindhu’s explanation of why realized bhakti (Bhāva-Bhakti) is so rare.
Śrī Rūpa explains that Bhāva-bhakti (realized bhakti) is so rare for two reasons: (1) It cannot be created by any effort, (2) it has to be received from Krishna, who is timidly reluctant about giving it, for in giving it he gives his very self.
This indicates certainly that Bhakti is not something we possess, nor something we even have the capacity to create. It is something we must obtain, something we must attract to manifest in our hearts.
In describing Vyasa’s Samādhi, Śrīmad Bhāgavatam also very clearly describes bhakti and jīva as distinct, different entities. Śrī Jīva analyses this section extensively in Tattva-Sandarbha. Bhagavān has three potencies, seen by Vyāsa as jīva (subjective consciousness), māyā (a me-based / selfish perception for consciousness), and bhakti (a Bhagavān-based / loving perception for consciousness). Neither māyā nor bhakti are “in” the jīva. The jīva, however, is “in” them! Vyāsa definitely saw the jīva situated in māyā, but saw that it could be placed in bhakti by a sādhana of hearing and chanting about Krishna.
Then what is “inherent and dormant within us”? The potential for bhakti is! Consciousness is designed to be an agent of bhakti, that is our essential and eternal svadharma and svarūpa (“Jīvera svarūpa hoya kṛṣṇera nitya dāsa”).
Here is a good analogy to clarify all this.
The jīva is like a garden field. Prema-bhakti is the flower. The seed for the flower is not inherent in the field of the garden, it has to come from somewhere else, but the potential to grow flowers is inherent, and you could say “dormant,” in the garden field – waiting for, needing the seed.