Devaiyanai
Goddess Devaiyanai is the daughter of God Indra, who assigned his white elephant Airavata or Airavatham, to take care of the baby. The elephant brought up the girl child with care and affection, and therefore she was named Deivayanai (Tamil-the divine one brought by the elephant).
The Goddess in her previous birth was Amritavalli, the daughter of Maha Vishnu. She along with her sibling Sundaravalli, undertook severe penance to become the consort of Lord Murugan. The Lord pleased by their devotion, appeared before them and gave the boon of marriage in their next birth.
Goddess Deivayanai represents 'Kriya Shakthi' or the "Power of Actions".
VALLI
Goddess Valli is the daughter of Nambi Raj (Nambirajan), the King of a Mountain tribe. Valli in her previous birth was the daughter of Lord Vishnu and did several penance in her previous birth to become to wife of Subramanya. Goddess Valli depicts the "Ichha Shakti" or "Power of Aspirations". The wedding of Valli to Lord Subramanya is called "Valli Kalyanam". It is said that after Valli Kalyanam Lord Muruga and Goddess Valli moved to Tiruthani Murugan Temple, one of the Arupadaiveedu of Muruga, located at Tiruttani, 50 km north of Chennai, Tamil Nadu. Valli Kalyanam is celebrated as an annual festival in all Lord Subramanya Temples on the Vaikasi Visakam day.
SOURCE : HINDU DEVOTIONAL BLOG