Kṛṣṇa is lion to the demons, and He's a lamb to the devotees.

Just like Prahlāda Mahārāja: he was a sādhu; he was being persecuted by his father. So Lord Nṛsiṁha-deva appeared, not for killing the Hiraṇyakaśipu, but to come and show Prahlāda Mahārāja, "Don't be afraid. I am here. Don't be afraid. I'll give you protection." So actually, Kṛṣṇa comes for this purpose, paritrāṇāya sādhūnām.

Śrīla Prabhupāda's lecture on Bhagavad-gītā 4.8 -- Bombay, March 28, 1974