In Hinduism, Harihara is a syncretism of two Lords, Vishnu (Hari) and Shiva (Hara). Lord Ayyappa is called Hariharasuta since he is the son of Hari (Vishnu), in the form of Mohini and Hara (Shiva).
The syncretic deity is an attempt to combine the worship of Shiva and Vishnu, the two polar Hindu deities, into a single object of devotion. In iconic representations , Harihara holds Shiva's trident on his right side and wears his hair in the Shiva ascetic (piled-up) style; on his left side, Harihara displays Vishnu's discus and wears a crown.
