Mitra & Varuna are the celestial duo to which we have been referring all along. Like Rudra and Maruts, they are Immortal – not of the physical body but by the liberation from avidya (ignorance of the true self). They possess amṛta and medicines – especially Varuna, who is addressed as the Physician, just like Rudra is called the Divine PhysicianVS16.5. They are also addressed as those with knowledge and intelligence KYV4.4.1,5.3.6 – like the Maruts, who are born in knowledge, and brahmāspati, lord of wisdomRV1.38.13. They are the Asuras of Heavens and are ugrā/manyu (terrible/fierce)RV1.24.6, yet benignant and benevolent. Like Rudra, Varuna at one time is addressed to have a thousand eyes RV7.34.10. Maruts are the winds and the bringers of rain (nourishment and food) and lightning-thunder KYV4.5.11, and so is Varuna (the rains). Maruts are the heroes and guardians of Heavens and Earth, the makers of Maya, and the guardians of ṛta (cosmic phenomenon). The cumulative spiritual nature of this cosmic duo is but a total impression of Rudra, but does such similarity justify them as Rudra RV5.61-72? Yes, the following hymns of Varuna-Mitra from Rig Veda Mandala 5 will clarify without ambiguity.
Rudra enters into various aspects of a Yajñá. For example, water is placed in vessels called Kalashas during a Yajñá, and Adityas and Rudra enter them. We have seen multiple times how Rudra enters into various aspects – like in medicines, into Soma, into Winds which are their arrows, into Vedic syllables, water, and so forth. The long-lost Caraka-Katha Āraṇyaka III-222 also addresses Mitra and Varuna as the eyes of Rudra which are the Sun and the fire.
ता वां सम्यगद्रुह्वाणेषमश्याम धायसे । वयं ते रुद्रा स्याम ॥ 5.70.2 tāǀvāmǀsamyakǀadruhvāṇāǀiṣamǀaśyāmaǀdhāyaseǀvayamǀteǀrudrāǀsyāma ǁ
Rig Veda 5.70
May you, oh benevolent divine, nourish and provide food for our living (through rains and generous winds) . Oh Rudras may we also become such.
पातं नो रुद्रा पायुभिरुत त्रायेथां सुत्रात्रा । तुर्याम दस्यूंतनूभिः ॥ 5.70.3
pātamǀnaḥǀrudrāǀpāyu-bhiḥǀutaǀtrāyethāmǀsu-trātrāǀturyāmaǀdasyūnǀtanūbhiḥ ǁ
Save us oh Rudras, guard us (पायु) with superior strength (तुर्याम) that can well protect us (सुत्रात्र) so that we can face the Dasyus (दस्यूं) on our own (तनू)
Om Namaḥ Śivāya 