Although Viśvarūpa was the son of the daughter of their eternal enemies the demons, the demigods accepted him as their priest in accordance with the order of Brahmā when they were abandoned by their spiritual master, Bṛhaspati, whom they had disrespected.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
तं वव्रिरे सुरगणा स्वस्रीयं द्विषतामपि । विमतेन परित्यक्ता गुरुणाङ्गिरसेन यत्
taṃ vavrire suragaṇā svasrīyaṃ dviṣatāmapi | vimatena parityaktā guruṇāṅgirasena yat
SB 6.6.45