Udayanapuram Subrahmaniya Swami Temple is just a kilometer away from Vaikom Mahadeva temple, near Vaikom in the Kottayam district and the deity is considered as the son of Lord Vaikathappan. The worship at Vaikom Mahadeva Temple is complete only with a sacred visit at the Udayanapuram temple also. Many devotees still visit the Udayanapuram temple prior to visiting Mahadeva temple as a custom and belief.
The legend, which I already scribbled when I put a post on Kumaranalloor Karthiyayani temple few years back, is that Cheraman Perumal decided to make a Karthiyayani devi temple at Udayanapuram and a Subrahmaniya temple at Kumaranalloor. Both the temple structures were almost finished and at the time of consecration, King heard a divine voice from the sanctum of Kumaranalloor temple which said that 'Kumaran Alla Ooril' (This place is not inhabited by Kumara, another name of Muruga) and with the help of astrologers it was revealed that Karthiyayani devi had already inhabited Kumaranalloor temple. Thus the consecration of Lord Muruga idol made for Kumaranalloor was later consecrated at Udayanapuram temple.
The architectural structure of the Udayanapuram temple is splendid and unique. There is a big temple pond found here after the Nalambalam which is not common in other temples. The festivals like Vaikathashtami and Kumaranalloor Thrikkarthika which are very famous across the state includes the celebration of Udayanapurathappan also due to the deity's relation with Vaikom Mahadeva temple and Kumaranalloor Karthyayani temple.
There is a grand procession of Lord Subrahmaniya from Udayanapuram to Vaikom temple and is in memory of Lord Muruga coming triumphant after killing demon Soora padma (mother of Soora Padma was sent to sage Kasyapa (generator of celestials) by Sukracharya (preceptor of demons) for the sake begetting sons in order to vanquish the celestials and therefore Soora Padma is considered as a born enemy of celestials) and is being welcomed by Gods, demi-Gods and other saints. The roads leading to Vaikom Mahadeva temple is electrically illuminated and on either sides lighted oil lamps will be positioned which will reflect an enticing hue on the thidambu of Lord Subramanya which will be portrayed as holding the divine weapon, the golden spear.
Thrikkarthika festival is also celebrated at Udayanapuram temple since it falls just one day before the Aarattu of annual celebration of Udayanapuram temple. The Aarattu at Udayanapuram temple is also a festival day at Vaikom Mahadeva temple since on Aarattu day Lord Subrahmaniya is brought in a procession to Mahadeva temple and certain rituals are performed for both the deities together and is known as "Koodi Pooja". Another interesting feature observed is that the Lord Vaikathappa going to the seat of Udayanapurathappan at Udayanapuram following the Aarattu ceremony. There again the holy bath and Koodi pooja get repetition.
Many materials offered to Subramaniya Swamy temple will be send to Vaikom temple as a custom (Presents from Son to beloved Father). But, directly offering an elephant is not allowed at Vaikom temple which has to be submitted at the Udayanapuram temple from where it will be later send to Vaikom temple.
The main nivedya at Udayanapuram temple is Poovan Pazham (a typical sweety banana) and the devotees pray to Udayanapurathappan that they will submit a particular number of Poovan Pazham to fulfill their wishes.
