Lord Vishnu changed his appearance to be able to follow Aryamala so he can eventually marry her.
Kathavarayan falls in love with a celestial girl named Ilankanni. When Kathavarayan tries to make love to her, she drowns herself. But she is reborn as a princess. She is named as Aryamala. Kathavarayan falls in love with Aryamala. He tries many tricks changing his form into creatures. But he takes his usual form and ties knot to Aryamala while she is sleeping. But Lord Vishnu saves her. However, Lord Vishnu intervenes and settles everything amicably. Kathavarayan and Aryamala are married and lived happily ever after. 
