Pradyumna: Translation: "Mahārāja Parīkṣit heard that out of His causeless mercy Lord Kṛṣṇa, or Viṣṇu, who is universally obeyed, rendered all kinds of service to the malleable sons of Pāṇḍu by accepting posts ranging from chariot driver to president to messenger, friend, night watchman, etc., according to the will of the Pāṇḍavas, obeying them like a servant and offering obeisances like one younger in years. When he heard this, Mahārāja Parīkṣit became overwhelmed with devotion to the lotus feet of the Lord." (SB 1.16.16)
Prabhupāda: So this is the exchange of love between the Lord and the devotee. It is not Kṛṣṇa, the Supreme Personality of Godhead... He's master, the Supreme, but we may not calculate the master and the Supreme by our material experience. Just like in our material experience we see the master is always master and the servant is always servant. But in the spiritual world, sometimes the master is the servant also. This is called Absolute, Absolute world. Here there is distinction between master and the servant, but in the spiritual world there is no such distinction. Sometimes the servant is rendering service to the Lord, and sometimes the Lord is serving to the master. Just like Kṛṣṇa, when He was playing with His friends, so they were sporting, and in the sporting there is defeat and victory. So if some of the friends would become victorious, then the challenge was that one who will be defeated, the victorious person will ride on his shoulder. That was the challenge. So when Kṛṣṇa became defeated, the other boys, they rose up and got up on the shoulder of Kṛṣṇa, and Kṛṣṇa had to carry them.