So much focus on the painful past which Ryudo could do nothing about. And Melfice, who could do nothing about his feeling that he lacked power.
Melfice is quite obviously IEI. As for Ryudo, he seems SEE in light of his fixation on his past. His EM type is IEI. When he says "true justice comes from the heart", what he really means is that "true justice" is what you feel in light of the pure heart that arises out of well lived Ni.
Elena is ESI. She is "possessed" by the Wings of Valmar, possessed by an organ in some larger purpose. It is fair to say that she is "possessed" by Te.
Millennia's vice is her hunger, which she can barely sate. It is her hunger for the organs, to be more complete. She "desires" them, therefore her vice is Fi and her type is LSE.
Interestingly I had thought that Millennia was something of a "doppleganger" to Elena, a reflection of her id. However, that doesn't appear to be the case. Millennia was designed as her own person with her own needs and wants, separate from Elena.
As a general rule when dealing with characters, the primary developmental needs of the individual determine the type.