Indra approached Vishwaroopa and requested Him to be his Guru. Roopa had advised Indra to beg pardon from his own Guru Brihaspati and go back into his fold. But Vishwaroopa, who had three heads, was of a queer character.
Roopa had one head, while Vishwaroopa had three heads. Having three heads was his biggest problem. Datta is a God with 3 heads. Here was a demon–human with 3 heads. With one head he would continuously eat meat, with the second he would continuously drink wine and with his third head he would eternally recite the Vedas. Such was the situation. Admiring him is akin to admiring a pig that wears a beautiful sari.
To a person who eats meat and drinks wine – i.e. the person who is of demonic traits, where is eligibility to recite Vedas? He can recite- the harm is not in recitation; but in judging the proper and improper use of this Vedic recitation. Vishwaroopa was excited to be appointed as the Guru of the Gods themselves! The Lord of heaven, the Lord of all Devatas had approached him- could there be any fortune greater than this, he thought? He was thrilled with this responsibility.
Vishwaroopa in his position as Guru, got Indra to perform many special rituals and Yagnas to attain prosperity. As part of those Yagnas, he even invoked Lord Dattatreya and ensured that Indra received the blessings of this Lord. He even taught Lord Indra the very powerful and sacred mantra known as Narayana Kavacham. With the initiation into the ever-powerful Narayana kavacham, it appeared as if Lord Indra was on the verge of victory.
So far so good, but Vishwaroopa had one weakness and it was his undying love towards his mother. His mother in turn had a soft-corner for her maternal relatives- the demons. Due to the pressure exerted by his mother, Vishwaroopa was silently hiding a portion of the results of the Yagna performed by Indra and diverting them to the demons.
To our eyes, the homa prasadam, the water in the sacred pot (kalasa) appears normal. But what our eyes cannot see is the hidden unimaginable power/energy that seeps into them during the process of homa.