Typically, Dharma Shaasta is shown with two consorts, namely Poorna and Pushkala. These names translate to "Completeness" and "Prosperity", and are allusions to the two paths — Jnaana and Bhakti, through which one reaches the Absolute as Self-Realization.
Rather than the two consorts, these represent the two halves of the Lord itself, in the pure Yogic posture and form one sees at Sabarimala.
The Lord is seen in a unique Yogic posture, sometimes also seen in Lord Narasimha, Dakshinamurthi or Aanjaneya. Here, the Lord is seated upright, with His legs bent and both ankles touching the Mooladhara or root Chakra. The erectness of the posture enables free flow of Kundalini Shakti or the Life force through the seven Chakras. It is humanly difficult to maintain such a posture for long duration, and to prevent the legs from straying away, the Lord has a band (Yoga Pattai) tying his legs with the back.
Thus, Chin-Mudra, or the gesture of concentration, consciousness and reality is the true and ultimate teaching of Self-Realization. One sees this exact same Mudra in the form of Dakshinamurthi. Thus, the right half of Dharma Shaasta highlights the teacher or Shaasta Aspect, and this is precisely Poorna Devi — completeness of wisdom, knowledge and understanding of reality.
The left hand of the Lord rests on His leg, pointing towards His feet . In all seated forms of Ayyappan, one will definitely see the left leg lifted up, irrespective of whether the right leg is lifted up (as in Yoga Asana form in Sabarimala) or hangs down (as in Veera Asana forms in other temples). Thus, depending on the height of the statue, when the devotee stands or sits before the Lord, he will find the Lord's raised feet at the level of the heart. This, and the Lord pointing to His feet, is His message to place His feet firmly in the heart (Hrudkamalam). The Lord as Krishna or Narayana says the same in the Bhagawad Gita — "Maam Ekam Sharanam Vraja".
Having the Lord's feet in the heart and constantly contemplating on Him is the cultivation of Bhakti or Divine Love, and this is also the easiest way to cultivate Sattva Guna, good conduct and Dharma, and ultimately reach the Lord. Thus, the left half of Dharma Shaasta highlights the righteousness or Bhakti or Dharma Aspect, and this is precisely Pushkala Devi.
Thus, the two consorts, or rather the two halves of the Lord signify the concept of Dharma-Shaasta with predominance of Narayana and Shankara aspects respectively.