Prahlada and the hill of the lion
The frame is the Narasimha story: Hiranyakashipu persecutes his son Prahlada for his devotion to Vishnu, and Vishnu appears as Narasimha to protect him. Simhachalam's tradition places Prahlada on this hill and explains the unusual image — Varaha and Narasimha in one form — from that episode. The specific sequence of the local account, and the text it comes from, are not yet told here.
Where this account comes from
We have not yet found a text we can cite for this account. It is told here as it is told locally, and marked unverified.