Upendran - Younger brother of Indran. He is none other than Vaamanan. Yes. One of the 10 avatars of Sri Maha vishnu. Why do I say him as the younger brother of Indran? Because, Vaamanan was born as the second son to Kashyapa Muni - Athithi couple.
Of the 10 popular avatars of Sri Maha Vishnu, it is in the Vaamana avatar, Vishnu manifests him as a brahmin boy and Upanayanam has been conducted for him. The upanayana brahmmopadesam of Sri Vaamana moorthi is well said in Sri Madh Bhagawatham.
The great ascetics and others who saw Vaamana moorthi in his upanayana ceremony, floated in the ocean of joy. Prajaapati was the head priest for the function. Surya, the sun god, performed the MantrOpadesam (chanting the Gayatri Mantra in the ears of Vaamana moorthi). Deva guru Brihaspathi gave the Brahmma Soothiram. His father Kashyapar gave the hip belt - Mekhala. Bhooma Devi, the goddess of the Earth offered the Deer skin which is considered to be a symbol of purity. Soma deva gave the Palaasa Dhandam, a stick to be held in the hand. Vaamana's mother Athithi gave the kowbeena vastram (cloth to wear). The lord of the Universe, Sri Parameswara offered an umbrella and Brahmma gifted the kamandalam or a stick that is used to support hands while doing Japam.
The seven rishis (Gritsamada, Vishvamitra, Vamadeva, Atri, Angirasa, Bharadvaja, Vasishta) gave the dharbai (a grass that is used for sacrifices or ceremonies) and Goddess Saraswathi gave the Japa mala (Garland used to keep track the number of times a mantra has been chanted). Kuberan, the lord of wealth presented a vessel (Biksha Paathiram) in which the great mother Uma devi offered rice.
So every person to who this Upanayana Brahmmopadesam is performed, acquires the status of Vaamana moorthi and the people involved in the above activities during the ceremony is transformed to the roles mentioned above. Such a sanctity is embedded in such functions. Hence let us not degrade ourselves by talking unnecessary things or passing mundane comments about the rituals and vain our lives. Do every thing with uttermost sincerity.