It’s sad that both Furina and Focalors suffered because of Fontaine’s prophecy, just in different ways. I often see people blaming Focalors for Furina’s 500 years of suffering, but Focalors suffered as well. She inherited a crisis she didn’t create and had to carry the responsibility of saving an entire nation.
I don’t think Egeria deserves all the blame either. The true root of Fontaine’s tragedy was the Heavenly Principles, whose punishment fell on innocent people. Egeria made a grave mistake by creating human life without the authority to do so, which led to Fontaine’s “original sin” and the prophecy. However, she also entrusted Fontaine to someone she believed could solve the impossible.
Focalors’ greatest strength was her strategic genius. While Egeria was wise herself and compassionate, Focalors was the one who devised a plan capable of deceiving the Heavenly Principles and saving Fontaine’s people. I like to think she may have wondered, “Why do I have to be the one to suffer?” But she chose to accept it because she believed her people’s lives mattered more than her own. She even expressed her desire to judge the Heavenly Principles for their own doings during the Archon Quest.
To me, that’s what makes Focalors one of the smartest characters in Genshin. If the prophecy was like a puzzle, then Egeria was the one who scattered the pieces, while Focalors was the one who figured out how to put them back together and achieve the only ending where Fontaine could be saved.