Maharaja Somadeva is the former Maharaja of Mahishmati, he is a able ruler and is the father of Bijjaladeva and Vikramadeva Mahadeva. His personal slave is Malayappa, who is the father of Kattappa and Shivappa. His wife is Maharani Hemavati, a haughty and proud woman. It is revealed that King Somadeva had accomplished many during his rein. During the beginning of his rein, he succefully defeated the Kadaraimandalam Kingdom which had held Mahishmati as a vassal state, he was able to establish freedom for Mahishmathi and do great business with the Gaurikanta stones which he had got from the Amma Gauri mountain. But he also deceived his people as he countinued mining in the Amma Gauri mountain althugh he publically said he would stop the mining in the Amma Gauri mountain. He was able to defend the palace during the coup staged by the Vaithalikas, moreover he was able to behead Bhuturaya. Finally, he succesfully made Kadaraimandalam a vassal state to Mahishmati. But he was outsmarted and betreayed by his own son Bjjaladeva once again. Kandaraimandalam gained independence with the help of Bjjaladeva and Pattaraya. Somadeva was imprisoned and his other son Mahadeva was made blind. Gauriparvat also gained independence with Shivappa as it's king. His wife Maharani Hemativi commited sucide. He was stabbed and killed by Uthanga, a former orphan. Shortly after his death Pattaraya was imprisoned and Shivappa was long dead by then being killed by Kattappa. The mining facility was drowned and the mining at the gauriparvat mountains were ended.
The Book - Rise Of Sivagami
In the book, he order Sivagami's father "Devaraya" to be executed. Which leads to Sivagami's hatred towards the Mahishmati royals.