User blog comment:B214/Volume 23 discussion blog/@comment-30924344-20170409190547/@comment-31713670-20170411115233

Indra is probably pissed because his status as supreme god in the rig vedas were retconned and altered to a lesser god. He probably also feels humiliated by how his heroic feats were retconned, in the new sacred text where he is potrayed as a weak god that needs the trimurtis help to do anything, and he blames Shiva for it since he basically took his place as the supreme god.