Śukadeva Gosvāmī addressed King Parīkṣit thus: “My dear King, Lord Brahmā, Lord Viṣṇu and Lord Śiva, the principal trio of the material creation, are able to bless or curse anyone. Of this trio, Lord Brahmā and Lord Śiva are very easily satisfied but also very easily angered. When satisfied they give benedictions without consideration, and when angry they curse the devotee without consideration. But Lord Viṣṇu is not like that. Lord Viṣṇu is very considerate. Whenever a devotee wants something from Lord Viṣṇu, Lord Viṣṇu first considers whether such a benediction will ultimately be good for the devotee. Lord Viṣṇu never bestows any benediction which will ultimately prove disastrous to the devotee. By His transcendental nature, He is always merciful; therefore, before giving any benediction, He considers whether it will prove beneficial for the devotee. Since the Supreme Personality of Godhead is always merciful, even when it appears that He has killed a demon, or even when He apparently becomes angry toward a devotee, His actions are always auspicious. The Supreme Personality of Godhead is therefore known as all-good. Whatever He does is good.”
As for the benedictions given by demigods like Lord Śiva, there is the following historical incident cited by great sages. Once, Lord Śiva, after giving a benediction to a demon named Vṛkāsura, the son of Śakuni, was himself entrapped in a very dangerous position. Vṛkāsura was searching after a benediction and trying to decide which of the three presiding deities to worship in order to get it. In the meantime he happened to meet the great sage Nārada and consulted with him as to whom he should approach to achieve quick results from his austerity. He inquired, “Of the three deities, namely Lord Brahmā, Lord Viṣṇu and Lord Śiva, who is most quickly satisfied?” Nārada could understand the plan of the demon, and he advised him, “You had better worship Lord Śiva; then you will quickly get the desired result. Lord Śiva is very quickly satisfied and very quickly dissatisfied also. So you try to satisfy Lord Śiva.” Nārada also cited instances wherein demons like Rāvaṇa and Bāṇāsura were enriched with great opulences simply by satisfying Lord Śiva with prayers. Because the great sage Nārada was aware of the nature of the demon Vṛkāsura, he did not advise him to approach Viṣṇu or Lord Brahmā. Persons such as Vṛkāsura, who are situated in the material mode of ignorance, cannot stick to the worship of Viṣṇu.