Helseth was the first child of Queen Barenziah of Wayrest and her husband Symmachus, in 3E 376. He is the older brother of Morgiah.
"If there is to be a revolution, it is best done by a King." ―Helseth Hlaalu[src]
At around the same time, the ancient goddess of Morrowind, Lady Almalexia, opposed him. She knew that Helseth, with his cunning mind, would take over Morrowind for himself, but she could not risk open war.
Then, the Nerevarine emerged. At first, Helseth saw the Nerevarine as another threat to his newly established monarchy. He hired the Dark Brotherhood to assassinate the Nerevarine. The Nerevarine proved to be mightier than any assassin the Dark Brotherhood could muster, and Helseth met the Nerevarine face to face.
Through clever manipulation, Helseth used the Nerevarine to turn the tide and eliminate all of the problems his new monarchy faced, allowing him to rule Morrowind undisputed.