Who is King Helgi?

I am currently writing King Helgi as a prequel in the Aristid Universe. This is based on The Saga of King Hrolf Kraki, an oral story told around 5th or 6th century, with later stories published around the 13th century.

Helgi was the young son of King Halfdan. He also had a brother named Hroar, and a sister, Signey.

The story of King Helgi is a difficult and violent one. It has elements of Hamlet some one thousand years before the bard wrote it.  

Without giving too much away, an uncle kills their father, causing the boys to flee the kingdom or fall under the blade themselves. In exile, they plan revenge. 

Afterwards, Helgi becomes a Danish King and his brother Hroar becomes a legendary ruler.  In the famous epic poem,  Beowulf appears before Hroar, known as Hrothgar, the Danish king whose kingdom is under assault from Grendel. 

About the Saga of King Hrolf Kraki:

https://viking.ucla.edu/excerpts/hrolf/abouthrolf.html

King Helgi is currently on Royal Road:

https://www.royalroad.com/fiction/180275/king-helgi