Hmm. So, Rudra is a name of Vishnu, the ruler of the gods of India (in his form of the Great Destruction that destroys everything at the end of time), but it's also a name given to Shiva in many later iterations as well; hymn 10.92 of the Rigveda indicates how Shiva was the kind and tranquil side and Rudra was his violent, destructive side, and that they are different incarnations of the same god. Shiva is also associated with Indra, as well. So most likely what ends up happening is a Potara where Rudra dies and Shiva absorbs him, or something similar, given how this novel likes to work.