As per the folklore, Lord Subramanya had imprisoned Lord Brahma for knowing the meaning for Pranava Mantra “Om”. Later on request of Lord Siva, he left Brahma and explained the meaning of Om to Lord Siva. To get rid of the sin, Lord Subramanya took the form of a serpent and started residing in an isolated well. The well was guarded by several other serpents to protect Lord from Sun and Rain. The place where Serpent guarded Lord Subramanya is Peralassery.Goddess Parvati requested Lord Siva to give the original form for her son. Lord Siva advised her to perform 18 Shasti Vrat to bring the original form for Subramanya. As instructed Goddess performed the Vrat and got her son in actual form.