Babruvahana, the son of Arjun, killed Vrishkethu, the son of Karna, in a duel after Karna’s death in the Kurukshetra war. The reason behind this duel is a bit complicated, but it can be summarized as follows:

• Karna’s son Vrishkethu was a skilled warrior and a formidable opponent. He was known for his bravery and his mastery of various weapons.
• Arjun’s son Babruvahana was also a skilled warrior, but he was still young and inexperienced. He was eager to prove himself and to gain recognition from his father.
• After Karna’s death in the Kurukshetra war, Vrishkethu vowed to avenge his father’s death. He sought out Arjun and challenged him to a duel.
• Arjun, being a wise and experienced warrior, knew that a duel with Vrishkethu would be unnecessary and dangerous. He tried to reason with Vrishkethu, but to no avail.
• As a last resort, Arjun sent his son Babruvahana to fight Vrishkethu in his place. Babruvahana reluctantly accepted the challenge.
• The duel between Babruvahana and Vrishkethu was fierce and bloody. Both warriors fought valiantly, but in the end, Babruvahana emerged victorious.

There are several different versions of the story of Babruvahana and Vrishkethu’s duel, but the underlying reason for the duel is always the same: revenge. Vrishkethu sought to avenge his father’s death, and Babruvahana felt obligated to fight in defense of his father. The duel is a tragic reminder of the cycle of violence that can be perpetuated by the desire for revenge.