Adding some twist to the folklore.
A little backstory :
Disproving of the result of the race around the world, Kartikeya blamed everyone of prejudice and claimed only he was capable of being the primary deity of the 2nd generation. "I have defeated the fiercest of the Asuras, i am the Devasenapati, who fights the battles for the Devatas. Indra needs my protection to be on the throne of Swarga. Its me who was the quickest to complete 3 rounds around the world. Fluffiness, cuteness and love for modaks were never a criteria for this competition" He said.
Ganesha being humble, told he never wanted the position of the primary deity and he was willing to give it to Kartikeya.
"You dont act nice with me, i know how smart you are" Kartikeya replied. "You want everyone to think you gifted this to me. You think i am a fool?"
"I want you to face me in a hand combat, a dwandwayudd. No astras, shastras or vahanas to rely on. Just your core strenght. Do you accept the challenge?
Take as much time to prepare yourself. Ages if you want to. Give me your best. And then lets see who is the most capable."
Ganesha was baffled with such reaction from his elder brother and accepted the challenge. It wasn't about being humble anymore. He left Kailash to prepare himself in the most grilling circumstances. Ganesha spent years training himself for the battle that was ahead. Slaying enemies became his second nature. He took down everyone, from the most notorious, to the world beaters.
He now felt he was ready... ready for the thing that changed him inside out. He called Kartikeya to Kailash, where it all began. After years of being alone and going through hell, Ganesha returned back. But nothing felt the same anymore. The scars of time and the effect of the venomous words spoken by his brother could be seen all over his body. There was no humbleness or humility left in him. He was not the same person anymore. Now it was all about winning.... the time for the ultimate showdown.
Ganesha took his stance..."Lets do this". He said.