Among the acts that have to be avoided, one should be wary of committing sins against the Lord's bhaktas for He holds them close to His heart and will not brook any harm befalling them. The Lord is equally disposed towards all jivatmas and has no personal foe. He remains unperturbed even when a Hiranyakasipu claims to be an opponent or a Sisupala hurls abusive names at Him. But He considers any offence towards His bhaktas, any form of Bhagavata Apachara, as unforgivable and deserving of severe punishment, pointed out Sri Asuri Madhavachariar in a discourse. So He unfailingly rushes to the aid of His bhaktas when they are threatened as in the case of Prahlada.
When questioned by Duryodhana why He had declined to accept his hospitality and had instead chosen to spend the night in Vidhura's humble abode, Krishna explains His stance in clear terms. Krishna says the Pandavas are His very breath. They are close to His heart and He would always protect them. Duryodhana being an open enemy of the Pandavas automatically is also His enemy.
During the Rama Ravana Yuddha, when Rama and Lakshmana, borne by Hanuman on his shoulders, are engaged in a fierce fight, Hanuman takes on himself the dreadful arrows of Ravana. Rama, realising this, is angered to such an extent that He decides to finally bring the long drawn out battle to an end by killing Ravana without any delay. Likewise, Rama is very much upset when Sugriva, on an impulse, rushes to Ravana's palace, fights a fierce duel with him and gets back to Rama's presence. Had anything untoward happened to Sugriva owing to Ravana's magical tactics of combat, Rama would be really be so heartbroken that even rescuing Sita would seem to be of no use.