Speaking of DF is it true that Lassic from the first PS knew about the Profound Darkness? I found the entire root of all evil ultimate bad guy theme puerile and I think it would have been more mature if DF was the summoning of everyone's collective vices and hatred manifested from another dimension. In other words, the selfish ambitions and colonialism of the Earthmen summoned Dark Force, and the Earthmen influenced him instead of the other way around.
Ironically, Dark Force from PSII was more challenging than the Profound Darkness from PSIV, I guess this shows how powerful Chaz and party are compared to the previous games

(or maybe how useful a dedicated healer like Raja is, but I did beat him with a party of four too)
PSIII has each new generation stronger than the last (e.g., level 50 Wren and level 10 third generation heroes have similar stats) so maybe this principle applies to the entire series?
"I've also thought of Dark Force being the one collective consciousness but able to inhabit multiple forms all at the same time."
That would make sense since he's a multidimensional entity.