Kaartikeya's reference comes in Raamaayan, Kishkindhaa Kaand, when Sugreev expresses his doubts as how Raam will kill Baali telling the stories of his might. Then Raam said - "My arrows are made of the material from Shar Van (Kaartikeya was born here).

Kaartikeya is the younger son of Shiv Jee from Gangaa - the elder sister of Paarvatee. The elder son of Shiv Jee is Ganesh Jee from Paarvatee Jee. Kaartikeya has several names - Shanmukh, Shadmukh, Shadaanan, Skand, Kumaar, Subramanyam.

As the legend goes on, when a long time passed to Shiv's marriage and no son was born to Him and Paarvatee, Devtaa went to Shiv Jee and requested Him for the son to kill Taarakaasur, as according to Brahmaa Jee's Vardaan, he was to be killed by Shiv Jee's son only and at the age of seven days only.

Hearing Devtaa's request Shiv Jee got ready to release His semen, but He asked Devtaa as "who will bear my semen?". Devtaa said "Gangaa will bear it." So Mahaa Dev released His semen and Gangaa bore it. But it was so powerful that she couldn't bear its heat. She asked Agni Dev as where she should keep it.

Now there was a Van in the foothills of Himaalaya called Shar Van (forest of reed). She left it there. Its heat melted the ice of Himaalaya, but nothing could flow out on the Earth, because it contained two essentials of Shiv Jee - Amrit (Ambrosia) and Halaahal (poison) which Shiv Jee kept in His throat since Saagar Manthan (churning of Milky Ocean) event.

Divinity does not give absolute Amrit or Halaahal Vish to mortals, so they stayed in that Shar Van. So each reed stem became a straw and contained both Amrit and Halaahal. And from the same forest Kaartikeya emerged.

When Kaartikeya was born, six Krittikaa took care of him and breast-fed him, that is why he is called Kaartikeya. And since they were six of them and all breast-fed him, it is said, Kaartikeya had six mouths to suckle on their breasts. That is why he was called as "Shadaanan", or "Shadmukh". As he was born to kill Taarakaasur, he killed him on the 7th day of his birth. He grew so soon that when he proceeded towards Taarakaasur's city, Taarakaasur didn't believe that Shiv Jee's 7-day old son could be so grown-up.

There are many stories about Kaartikeya. One is given here to show his intelligence. Once many Devtaa including Shiv Jee, Brahmaa Jee, and Kaartikeya were sitting in Indra's court. Bhringee Apsaraa was dancing there. Shiv Jee merely raised His eyebrows to stop the dance then looked at Kumaar once, then at Brahmaa. Brahmaa Jee immediately stood up and spoke - "You asked me to start the education of Kumaar, so I did and first I taught him "OM". He immediately asked the meaning of "OM". I said you should not ask the meaning of "OM" before learning it to write. 

He held my hand and he was about to beat me. Who killed Taarakaasur at the age of 7 days certainly wouldn't care for me so I explained the meaning of "OM" in 12,000 verses but he was not satisfied. He said to me "Brahmaa, you don't know anything". He is standing before you. I don't know more than I have already explained." Shiv Jee got very happy to know about His son's intelligence. Then Shiv Jee Himself explained its meaning in 1,200 thousand (12 Lakh, or 1,200,000) verses. Kaartikeya said - "It was wrong on my part to say that Brahmaa didn't know."

Shiv Jee understood Kaartikeya's sarcasm, that he was implying that Shiv Jee was also ignorant about the meaning of "OM". Shiv Jee got angry at this but was happy too in His heart to see His son's  intelligence. He asked "Then how many meanings are there of this word?" Kaartikeya said - "12 million (1 Crore and 20 Lakh, or 12,000,000)." So such is Kaartikeya.