Ishvara Puri's birthplace is popularly known by the name "Chaitanya Doba." The word doba means "a pool of water". When Chaitanya Mahaprabhu passed through Kuymara Hatta on His way to Puri, He showed respect for His spiritual master by picking up some earth from the place of his birth, wrapping it in his cloth and taking it with him. Thousands of pilgrims have since followed His example, thus forming a pit that has since filled with water.
Then the Lord went to Gaya where he met Ishvara Puri. After taking initiation from him, He started to display the signs of love of God, and when He returned to His homeland He began to engage in the pastimes of divine love.
(Chaitanya Charitamrita 1.17.8-9)
When they met, Mahaprabhu and Ishvara Puri were overcome by the ecstasy of love and drenched each other in tears of prema that fell from their eyes. The Lord said, "my pilgrimage to Gaya is successful for today I have seen your lotus feet. When one makes the pinda (offerings to the ancestors at a holy place), then that ancestor is delivered. But simply by seeing you, ten million ancestors are delivered from all forms of bondage in a single moment. Therefore no holy place is your equal, and you are the primary source of auspiciousness for even the holy places. Please lift Me up from the ocean of material suffering: I offer this body up to your service. The only gift I ask of you is that you give Me the nectar of Krishna's lotus feet to drink."
(Chaitanya Bhagavata 1.17.49-55)
Mahaprabhu was acting the role of an ordinary mortal, a pilgrim who had come to Gaya to offer the sraddha oblations for His deceased father. On the day that He performed these rituals, He returned to His room and began to cook. When Ishava Puri came and placed his holy feet in Mahaprabhu's room, Mahaprabhu personally served him the rice and vegetables that He Himself had cooked with great satisfaction. In so doing, Mahaprabhu demonstrated most perfectly how to serve the guru.
Once, Ishava Puri passed through Nabadwip when Nimai was still engaged in His pastimes as a student. He stayed there for a few months in the house of Gopinath Acharya as his guest. One day he saw Nimai and was most impressed and attracted by His bodily beauty. Nimai invited Ishava Puri to his house to eat and had His mother Sachi cook and serve Him Krishna prasad. Then He and Ishvara Puri began talking about Krishna.
Ishava Puri also met Gadadhar Pandit and was pleased when he saw the depth of his renunciation. He started to affectionately give him lessons from Sri-Krsna-lilamrta, a book of his own composition. Nimai would also come daily to Gopinath Acharya's house to visit Ishava Puri while he was teaching Gadadhar and offer him His obeisances. One day, Ishava Puripada asked Nimai to correct any mistakes that were in his book. Nimai answered:
"Anyone who finds any fault with a devotee's description of Krishna is a sinner. If a devotee writes a poem, no matter how poorly he does it, it will certainly contain his love for Krishna. A fool says 'visnaya' while a scholar knows the correct form is 'visnave', but Krishna accepts the sentiment in either case. If anyone sees a fault in this, the fault is his, for Krishna is pleased with anything the pure devotee says. You too describe the Lord with words of love, so what arrogant person would dare criticize anything that you have written?"
(Chaitanya Bhagavata 1.11.105-110)
The same incident is described in the Bhakti-ratnakara in the following way:
Look here, this is the house of Gopinath Acharya where Visvambhara would visit from time to time. Ishava Puri stayed here for a while and composed his book Sri Krsna-lilamrta. He had great affection for Gadadhara Pandit and when he saw the symptoms of love for Krishna in him, he taught him that book.
When Nityananda Prabhu as traveling in the west of India, he incidentally met Madhavendra Puri there. When the two met, they fainted. Nityananda was overcome by love and started to describe Madhavendra Puri's glories while Madhavendra Puri himself embraced Nityananda and wet him with his tears. Ishvara Puripada understood that Nityananda was extremely dear to his spiritual master and so, like his guru's other disciples, held him in great affection and felt a deep love for him.
All glories to Madhava Puri, the ocean of love for Krishna! He was the first shoot of the desire tree of devotion. That first shoot was nourished and grew in the form of Ishvara Puri and from him the thick trunk of Chaitanya lila took shape.
(Chaitanya Caritamrita 1.9.10-11)
Before he left this world, Ishvara Puri sent two of his disciples, Kashisvara and Govinda, to serve Mahaprabhu. Even though they were His godbrothers, Mahaprabhu still obeyed the order of His spiritual master and accepted them as His servants.