Vajrasattva has father-mother ( Yab-Yum or Shakti) aspect too. Generally this form is not exhibited in open. It is shown only to those who are initiated in Highest Yoga Tantra. His form is the same as in the single one but his consort carries a kartrika in her right hand and a kapala in her left hand.
Vajrasattva is said to have been originated from seed syllable Hum and is generally invoked for removal of obscuration of conflicting emotions (Kleshavarana) and obstruction to Omniscience (Jneyavarana).
The first opponent power is the force of reliance. This means looking upon the visualized image of Vajrasattva as the embodiment of one’s refuge.
The second opponent power is the sincere regret for the non-virtuous action done by oneself.
The third opponent power is desisting from evil deeds.
The fourth opponent power is to apply power of good deeds; and specially regarding this case, practicing the meditation and recitation of Vajrasattva without parting from Bodhicitta while remaining in the state of emptiness.
Vajra-sattva hundred syllable mantra (right picture) is very efficacious in purifying our defilements through confession practice. It is said if confession is done with the four opponent powers, then non-virtuous actions or obscurations will be purified.
Vajra-sattva is a very popular tutelary deity for Nepalese Vajracaryas. He is worshipped very often by Nepalese Buddhists through Gurumandala ritual. The Svabhavika sect in Nepal identified Swabhava or Swa [own], bhava [nature] Adi-Buddha with Vajrasattva, who, according to the Nepalese Buddhist writings, manifested himself on Mount Sumeru in the following manner. A lotus-flower of precious jewels appeared on the summit of mountain which is the center of the universe, and above it arose a moon-crescent upon which,' supremely exalted', was seated Vajrasattva.
Certain Lamaist sects identified Vajrasattva with Vajradhara, while others looked upon Vajrasattva as an active form of Vajradhara, who was too lost in divine quietude to occupy him directly with the affairs of sentient beings. Visit the link to read about Vajradhara, Bajra satwa พระโพธิสัตว์วัชรสัตโต