In the Puranas, it is said that in the later ages (Kaliyuga perhaps), even an ordinary man/king can acquire the position of Indra, the king of gods. The Vishnu Purana has the following story which tells us how a mortal king became an Indra. Once there was a bitter war between the gods and the demons. The war went on for a while and there seemed to be no resolution in sight. Finally, both sides approached Brahma the creator and asked him who would eventually win this apparently unending war. Brahma thought for a while and said, “The side that the King Raji, who rules the earth, supports by taking up arms on its behalf will win this war”.
The demons were quick to approach Raji and asked him to aid them in the war. King Raji agreed but on one condition. After the war, he said, he wanted to be crowned Indra. Now the demons were in a fix. How could they possibly guarantee the kingdom of gods, even more so because Indra Prahlad’s term was not yet over? Dejected, they withdrew in disappointment.
The gods came in next with same proposition. King Raji put forth the same condition. The gods agreed at once and soon Raji joined their army and as predicted, helped them win the war. Indra had to step down and accept Raji as the supreme king of the gods. He bowed before him and placing his foot on his head said, “You have saved me from great danger, I acknowledge you as my superior and my king. From now you will be known as Indra”. But Raji was content to remain on earth and so he asked Indra to continue as his representative on the throne of heavens. Indra agreed. So even though Indra performed all the kingly duties, the oblations and sacrifices reached Raji. Although Indra was unhappy, he could do little but accept the situation since that had been the condition the gods had accepted for their victory.
However matters got out of hand when Raji’s son wanted to perpetuate the arrangement after his father’s death. Indra opposed this idea but was compelled to yield at the end. Sad and frustrated, he went to his teacher Brihaspati and asked him for a morsel of the sacrificial butter. Brihaspati was sad to see Indra’s plight and said, “Had you been courageous enough to win the war for gods earlier, you would not have ended up thus. But I can help you to regain your sovereignty.”
Brihaspati set up a yagna for Indra which would help him regain his lost powers. The yagna made Raji’s sons arrogant, they began mocking the Vedas and neglected their religious duties and ended up as enemies of gods. And at a point when they had become too weak to put up a valiant fight, Brihaspati advised Indra to kill them and reclaim his position as the king of gods.

Story collected by: Vidya Kamat
Text source: Vishnu Purana – Book IV. Chapter IX
Location: Pan India
Image details: Indra (MATHURA), Collection of Metropolitan Museum of Art
Image Source: Wikipedia