Babruvahana is the son of Arjuna and Chitrangada. It so happened that, before Dharmaraja did the Rajasuya sacrifice, Sage Narada came as per the instructions of Lord Brahma. The purpose of His arrival was to warn the Pandavas about not getting into a quarrel over one wife. All the 5 Pandava brothers were married to Draupadi, the daughter of King Drupada. Now, due to one beautiful wife, the Pandavas could quarrel with each other over her. So, to prevent that, Sage Narada came to Indraprastha and told Dharmaraja his purpose of arrival.
He narrated the story of Sunda and Upasunda and how they were killed by their own lust over Tilottama, the celestial damsel created by Vishvakarma. Sage Narada, as per Lord Brahma’s instructions, asked Dharmaraja to follow a rule, which is: Every Pandava brother stays with Draupadi for a year. For example, for one year, Dharmaraja and Draupadi, then another year, Bheemasena and Draupadi, then Arjuna and Draupadi, the next year, and so on. Dharmaraja agreed to this, and Sage Narada departed.
After this, Dharmaraja had a pact with his brothers that each brother would stay along with Draupadi for a whole year as per the instructions of Sage Narada and Lord Brahma. Plus, they even made a rule that if any other Pandava brother sees a particular Pandava with Draupadi, like, for example, in the first year, Dharmaraja and Draupadi are together, and if Bheemasena, Arjuna, Nakula, or Sahadeva saw them together in solitude, then that particular Pandava brother who saw both would go on a sacred pilgrimage for a whole year.
Once, when Dharmaraja and Draupadi were together in the weaponry room. Arjuna too came there accidentally at that time and saw both. Actually, it was like a Brahmin had come to Arjuna seeking protection from thieves, so Arjuna had come there to take his bow and arrow. He accidentally saw Draupadi and Dharmaraja together. After protecting the Brahmin, Arjuna came back and told Dharmaraja that he was leaving for a pilgrimage all over India as a result of seeing Dharmaraja and Draupadi together. Dharmaraja initially asked Arjuna not to go, because his seeing them was not intentional and hence was not necessary for him, but Arjuna insisted on going for the pilgrimage, to which Dharmaraja finally agreed.
Arjuna went for his pilgrimage, and during his pilgrimage, he married Uloopi, who was a Naagakanya. After that, Arjuna came to Manaloor in the South, the capital of the Pandya kingdom. There, King Chitravahana ruled. He had a beautiful daughter by the name Chitrangada. Arjuna fell in love with Chitrangada and married her. Arjuna stayed with her for 3 months. They both had a son by the name Babruvahana. After that, Arjuna left from there. And from then on, Chitrangada never met Arjuna until the Ashvamedha Sacrifice in future.
SriMadhvacharya says in the Mahabharata Tatparya Nirnaya that Arjuna is Indra and Chitrangada was Shachi Devi's incarnation. Since in the previous birth, this Chitrangada was Tara and Arjuna was Vaali. After the death of Vaali, Taara stayed along with Sugriva and accepted him as her husband. After the Ramavatara, when Tara in her Shachi form went to Svarga, she wasn’t allowed in, saying that since she stayed with another person after her husband Vaali’s death, she won’t be allowed to enter Svarga. She was separated from Indra for 100 years as a result of such an act. Plus, this Tara or Shachidevi was born as Chitrangada in the Dvaparayuga and married Arjuna, but due to the previous birth's karma, she had to suffer separation from Arjuna.
After that, Sahadeva met Babruvahana during his Dakshina Digvijaya, before the Rajasuya Sacrifice, during which Sahadeva also gifted Babruvahana many gifts and received tax from King Chitravahana. In the Ashvamedhika Parva of the Vyasa Mahabharata and the Mahabharata Tatparya Nirnaya of SriMadhvacharya, it is stated that, when Dharmaraja performed the Ashvamedha sacrifice, he appointed Arjuna for the protection of the horse. Thus, Arjuna came to Manaloor, and Babruvahana identified his father and welcomed him with arghya, paadya, and all. Arjuna didn’t like it and asked him to fight him.
Uloopi, the wife of Arjuna, appeared in front of him and said to Babruvahana, “You must perform what pleases your father.” And hence asked him to fight his father. Both fought. Arjuna, out of his love for his son, fought mildly, but Babruvahana, due to his childishness, released a divine arrow at Arjuna, which stuck him and made him unconscious. At that time, Uloopi was there. Chitrangada came there. She was very devastated on seeing Arjuna unconscious. She was very angry at Uloopi and said, “Fie you! Due to you only, father and son fought, and a father got killed by his own son.” Chitrangada, in her mind, thought of leaving her mortal body, but was stopped by Uloopi.
Uloopi went to Nagaloka and brought Vishalyakarani medicine and applied it on Arjuna. Arjuna woke up again. Uloopi said, “I had heard a conversation in the devaloka where the devatas were speaking thus: ’ Earlier, Bhishma and others were not killed righteously by Arjuna. Thus, he needs to experience immense pain.’ So, ensuring nobody else caused this pain, I asked Babruvahana to engage in the war so that the words of the devatas come true.”
Uloopi said, “It is due to the resolve of the Devatas that he fell unconscious. Since he has experienced the results of his mistakes, there shall be no occasion to experience it through others. If Arjuna had lost to others, his fame, which is spread all over the three worlds, would have been tainted. Devatas did thus to ensure his fame does not suffer any loss. When Uloopi narrated thus, Arjuna became affectionate towards his wife and son. Having invited both of them to the Yajna, he proceeded further.
So, this was the story of Babruvahana, like how he was born and what he did. Hope this helps!
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