Ramanuja, also known as Ramanujacharya, was a Hindu philosopher and theologian who lived in the 11th and 12th century in South India. He is considered to be one of the most important proponents of Vishishtadvaita Vedanta, a school of Hindu philosophy that emphasizes the concept of unity and oneness with God. As such, the relationship between Ramanuja and Vishnu is a central aspect of his teachings.

According to Ramanuja, Vishnu is the supreme deity and the ultimate reality. He is the source of all existence and the ultimate goal of human life. Ramanuja believed that the relationship between the individual soul and Vishnu is one of inseparable and eternal love. He taught that through devotion and surrender to Vishnu, one can attain liberation and become one with him.

Ramanuja's philosophy is based on the concept of Vishishtadvaita, which means "qualified non-dualism". This means that while Vishnu is the ultimate reality, he also exists in a qualified form in the material world. Ramanuja believed that everything in the universe is a manifestation of Vishnu and is therefore connected to him. This relationship between the individual soul and Vishnu is known as the "qualified oneness" or "qualified non-dualism".

Ramanuja also emphasized the importance of bhakti, or devotion, in the relationship between the individual soul and Vishnu. He believed that through loving devotion and surrender to Vishnu, one can attain moksha, or liberation from the cycle of birth and death. This devotion can be expressed through various forms of worship, such as rituals, prayers, and chanting of Vishnu's name.

Ramanuja's teachings also highlight the concept of grace, or the divine mercy of Vishnu. He believed that it is only through the grace of Vishnu that one can attain liberation. This grace is not dependent on one's actions or knowledge, but on the love and devotion towards Vishnu.

In summary, the relationship between Ramanuja and Vishnu is one of deep love, devotion, and surrender. Ramanuja saw Vishnu as the ultimate reality and the source of all existence, and taught that through devotion and grace, one can attain oneness with him. His teachings continue to inspire and guide devotees of Vishnu to this day, and his philosophy remains an important part of Hinduism.