Though slightly varying versions occur in the Puranas, they broadly follow the same pattern. By this period, the identification of Shiva/Rudra with Agni, that can be traced back to the Vedas and Brahmanas, had clearly made Karthikeya the son of Shiva.
The Skanda Purana narrates that Shiva first wed Dakshayani (also named Sati), the granddaughter of Brahma, and the daughter of Daksha. Daksha never liked Shiva, who, symbolizing destruction and detachment, begs for food, dances in a graveyard smeared with ashes, and has no possessions, not even good clothes for himself. Daksha publicly insults Shiva in a Yagna ceremony, and Dakshayani immolates herself. The Yagna is destroyed although protected by all the other Gods and the rishis. Taraka believed that, because Shiva is an ascetic and his earlier marriage was conducted with great difficulty, his remarriage was out of the question, hence his boon of being killed by Shiva's son alone would give him invincibility.
The Devas manage to get Shiva married to Parvati (who was Dakshayani, reborn), by making Manmatha (also known as Kama), the God of love awaken him from his penance, but Manmatha incurred the Lord's wrath indicated by the opening his third eye - "Netri Kann" , and being destroyed & resurrected. Shiva hands over his effulgence of the third eye used to destroy Manmatha to Agni, as he alone is capable of handling it until it becomes the desired offspring. But even Agni, tortured by its heat, hands it over to Ganga who in turn deposits it in a lake in a forest of reeds (shara). The child is finally born in this forest (vana) with six faces-eesanam, sathpurusham, vamadevam, agoram, sathyojatham and adhomugam. He is first spotted and cared for by six women representing the Pleiades - Kritika in Sanskrit. He thus gets named Karthikeya. As a young lad, he destroys Taraka. He is also called Kumara (Sanskrit for "youth