Sounds interesting... also Mithra!
I was looking for something new to watch, last time I've stopped to watch something was in March when I've watched the Four Seasons of The Expanse in a row.
I always thought as Mithra being one "Asura" from Zoroastrianism, I didn't know that there was also a divinity with the same name in Roman Mythology. In fact in a quick search I've found that this name is used in a lot of religions.
Talking about Zoroastrianism, for those who are not familiar with it, it's a very interesting religion.
During the Islamic expanse on Persia, Islam did not fight against Zoroastrianism religion as they interpreted it as the same religion as Islam, all the Zoroastrian temples and religion members were not "touched". In fact, there is a famous Temple of Fire were the "Eternal Flame" still burning for more than 1550 years (there are clerics devoted to maintain the flame burning).
You can search for Yazd Fire Temple or Yazd Atash Behram for more information for one of the most famous temples. There is some others Fire Temples that stills, like in India and some other countries. There is some reports about it and also videos and pictures. The Temples are beautiful and for sure could serve as inspiration for some adventures, civilizations or religions in a Fantasy Settings.