This is a story about the god Ayyappa/Manikantan who is the main God at the famous Sabrimala temple. Able people from all over South India attempt to climb the mountain to reach this temple every year. The story told is that lord Ayyappa was created to kill a demoness Mahishi who had been granted a boon by Brahma that she intended to misuse.

 

Ayyappa as a baby was found one day by the king of the kingdom Pandalam abandoned in the forest. As the king and queen were childless, they adopted Ayyappa. However, a few years later they gave birth to a child of their own. The queen began to favour this child over Ayyappa, and she was not okay with the King's decision to make Ayyappa the heir to the throne as she believed her biological son was the rightful heir.

 

In an attempt to get rid of Ayyappa, she asks Ayyappa to go into the forest to get her the milk of a Tigress which she claimed was the only cure to an illness she claimed to have. She believed that this would be the easiest way to get rid of him as he would be devoured by the tigers, and she wouldn't be directly responsible for his death. Ayyappa set out into the forest alone to help his mother out and on the he encountered the demoness he was destined to kill, Mahishi.

 

He not only served his destiny by killing her, but he also returned to the kingdom mounted on a tigress, further escorted by a group of tigers behind him. The Queen was shocked to see that he was still alive and not only did the tigers not attack him, but they were also somehow drawn to him, and he had his way with them as well. Even to this day every imagined image of Lord Ayyappa has him mounted on a Tigress. Most Hindu gods have a vehicle or Vahana as you call it and Lord Ayyappa's Vahana is a Tigress.

 

Some other variations say that Indra and other Devas came to his aid in the form of tigers. Also, Ayyappa is said to be the son of Vishnu and Shiva, and his true form was revealed to the kingdom when he returned to the palace with the tigers. And although most people fled in fear, the king was so relieved to see his son, he wasn't afraid of the tigers. Ayyappa eventually declined the opportunity to be the next king and resided in Sabrimala.