Skanda Purana, the religious text about the life of the lord, gives a good account of the interesting legend on the birth of Muruga and his exploits.
The advent of Muruga became necessary for saving the universe from the atrocities of the mighty demon, Surapadma, who obtained many boons, became quite powerful and started oppressing even the Gods. The compassionate Lord Shiva opened his third eye, and a blazing flame emerged out of it. The divine forces carried this to the sacred pond, Saravana Poigai, where, the flame transformed into six sparks and six handsome babies emerged out of them. These six divine babies were well taken care of by six angels known as Karthigai Pengal (damsels), who were the personifications of the powerful star Krittika. As Goddess Parvati very fondly hugged the six young ones together, they all merged into a single form, with six heads. Pleased with the service of the angels, the divine couple Shiva and Parvati, named the baby as Karthikeya. Vaikasi Visakam that is, the day of Visaka star in the Tamil month of Vaikasi (mid-May to mid-June) is considered the day of the Lord’s incarnation, while all the Krittika star days are held sacred for Muruga worship.
Then Muruga set out on his mission of ridding the universe of evil forces. Armed with the mighty Vel (lance), presented to him by his mother Parvati, Muruga led an army of celestial beings against the demon army and fought Surapadma, his henchmen, and their mighty forces. The fierce battle ended on the 6th day, when Lord Muruga comprehensively defeated Surapadma and his evil forces, relieving the Gods and the people, of his repression. This Shasti day, that is, the 6th day of the waxing moon is observed as Skanda Shasti, in the Tamil month of Aippasi (mid-October to mid-November). The grateful devotees remember the heroic feat of Muruga, sing his glory for the first five days, and on the 6th Skanda Sashti day, they undertake Vrat or fasting and offer him special worship to commemorate his resounding victory. This triumph is also enacted in many Muruga temples with enthusiasm as ‘Soorasamharam,’ the annihilation of Surapadma.
But the merciful Lord, didn’t actually kill Surapadma, but only destroyed the evil in him, and accepted the chastised demon as his devotee. In the last phase of the battle, Surapadma realized that his opponent was none other than the invincible Muruga, and began changing himself into different forms, using his illusory powers. But these were of no avail. Ultimately he became a big mango tree, which Muruga split into two, with his Vel. As a very last effort, the demon converted himself into a peacock and rooster, from the two tree pieces. Muruga not only tamed both in no time but also showed his compassion by accepting the peacock as his vehicle and transformed the rooster into his flag’s symbol.
The legend of Muruga illustrates the great truth that anyone repenting sincerely for his or her sins and praying for redemption would receive divine pardon and blessings.