Sastha is Ayyappa and is widely worshipped in Kerala and parts of Tamil Nadu and Karnataka. Sastha is the son of Shiva and Vishnumaya. As per some stories Kuttichathan is also the son of Shiva and Vishnumaya. Some scholars are of the view that Sastha and Kuttichathan are the same.
Kuttichathan is widely worshipped by black magic practitioners as He has the power to provide anything. Chathan can also change into any form. Kuttichathan is the son of Shiva.
As per some stories Chathan is the son of Goddess Parvati and Shiva.
As per another set of stories, Chathan is the son of Shiva and Mohini Avatar of Bhagavan Vishnu. Mohini Avatar is also referred to as Vishnumaya in some stories.
As per some scholars, Sastha is the son of Shiva and Mohini Avatar of Bhagavan Vishnu. Sastha might have undergone pronunciation change over a period of time and might have changed to Chathan. They also argue that Sastha when pronounced in certain local dialect sound like Chathan.