coz he is a shiv-bhakt,son of saptrishi,Jamadagni and related to the tridev..
Avatar or incarnation of Vishnu
Disciple/pupil of Shiva
and a descendant of Brahma...
Next,
this character had cursed Devi Parvati, and the character's husband would be born as the son of an incarnation/avatar of Lord Vishnu...