What is the nature of Lord Narayana's form, when He takes avataras? While those of us on earth have bodies that are made up of Satva, Rajas and Tamas, His form is always pure Satva, said Adur Asuri Madhavachari. Swami Desika points out that in all His avataras, whether as Rama or Krishna or Trivikrama, He retains all these auspicious qualities, thereby demonstrating His Supremacy. Lord Narayana is the opposite of all bad qualities, and the embodiment of all good ones.
But those who still harbour doubts, then turn their attention to the Narsasimha avatara, and wonder how the half- man, half- lion form is also auspicious. There need be no doubts on this count. It is one of the three complete avataras, the other two being the Rama and Krishana avataras. In the Vishnu Sahasranama, it is the Narasimha avatara that is mentioned first among all the avataras. Narasimha came heeding the calls of a child, and that too the child of an asura.
It is said that Lord Narayana came as Narasimha for the sake of Prahlada. But a better way of putting it would be to say that He came in order that Prahlada's words might be proved true. The Lord is always true to His words. He never slips from them. Nor does He let his devotees' words prove false. Prahlada had declared to his father Hiranyakasipu that the Lord was there everywhere. That is why the Lord took His position in all pillars, for He wanted to be at hand, whichever pillar Hiranayakasipu chose to strike. He wanted to show that He would never allow His devotees' words to be proved false. Whatever form pleases His bhaktas, is a form that He readily assumes, and in doing so, the Lord loses none of His auspicious qualities. His form remains always pure and untainted.
Nammazhvar shows this to us, by saying that He is the One who is on earth, heaven and also in the space between heaven and earth. He is one and the same everywhere, with no dilution in His qualities. His form is pure everywhere and at all times. He is unmatched and Supreme, and yet simplicity is His defining quality. Else would He hasten to the side of Prahlada, in His half-man, half-lion form?