dorian gray historical references

getting stuck in the history lesson section of this book, many references i am not familiar with.

i looked up “Ezzelin, son of The Fiend, as was reported, and one who cheated his father at dice when gambling with him for his own soul.”

is Ezzelin the italian feudal lord tyrant Ezzelino III da Romano in 13th century? i see nothing about his father being ‘“the fiend” or how he would have garnered that metonym.