Boy, more questions? Very well, I try answer along.
Regarding Metheus
Unfortunately, he got the fate of a side character, where he is pretty much ignored safe for a path or two. If anything, he continues to serve Frederone in many routes, safe for the worst route, perhaps.
Regarding Krotus
Frederone and other liches receive power directly from Krotus, unless Krotus permanently grants it to him, during the servitude and bad routes. So yes, if Krotus is weakened in any way, so will Frederone. Thus, killing Krotus will indirectly kill Frederone, thus what happened in True Ending.
As for sequel
I doubt I really got much stuff to write about it, given that most characters have ceased to exist. No, I definitely don't want a Winter Shard Death and Winter Shard Rebirth. Perhaps a flash animation remake with a 3rd person's point of view, but definitely not a sequel.
Well, the art is pretty what that keeps on griping me. As an artist, I tend to compare my works with others, and will always got the "Dang, still not good enough" feeling. Some of the scenes have undergone numerous remake before the "Ok" version is out.
As for the shards
I want to make it a rather mystical phenomenon which is left unexplained. Sure, there might be a possibility that they still contains a hint of Frederone's power, but I doubt anyone who will dare to try to experiment with it else invoking the Frozen Lich back.
Regarding True Ending
I will say that it is Frederone's willpower that allows him to track Marliene. Sure, I could just write that he totally vanished when Krotus is gone, but that won't make for a pretty finale, no?
At the end of True Ending, with the undead vanquished, Northern is no longer under siege. Thus, the humans living there began to notice that they are "safe", with some still traumatized.
As for a demon hierarchy
To be honest, no. During design phase, Krotus is the only demon summoned, and none others are above him or so. No, there is no Archimondes or someone similar.
For the Krotus' ruling
Being once a mortal himself, Krotus knows of living as one. Thus, this allows him to set out regulations acceptable by the people. Resistances might submit, but that is where Frederone's task - To uphold the law.
As for the possibility of invasion, Krotus has no intention to spread his influence out of the continent. Other continent will not be that foolish to challenge Krotus else facing the peril of destruction.
For Frederone, in servitude routes, he has pretty much pledged his absolute loyalty to Krotus, that he has no desire to rebel against him, as quoted in the game.
Regarding the love
Frederone is always troubled. Even when Rosetta killed herself, at the midst of the hatred, he still loves her. This allows him to accept Marliene, even the bad routes.
Regarding the choices, it is pretty much my selfishness that allow Marliene to be acceptable even tainted. It is out of sympathy for my character.
As for the hunger
To be clichy, it is somewhat a problem which lesser lich suffers. As his body starts dying out, Frederone needs to re-warm himself consistently. That was done by gorging out others' blood, or just stealing away their warmth. When Krotus grants him permanent power, he is able to overcome such drawbacks.
As for Rosetta
I am pretty much making this a sort of loved one-or-work choices out of it, where Frederone needs to think which is more important. But uh.. I don't recall Krotus drainng off Rosetta.
Regarding her hair, yes, I feel that pink suits her well. Marliene's hair might look a little bad, given that it is blood red.
As for the glasses
It is something available in my storyline. Given that Frederic failed to be a swordman, he work in a apothecary to learn about medical. Glasses is there to reflect his strive to learn.
Heh, as for the Worst Ending
I wanted to include an image of Frederone's face smiling wickedly above the altar. Let's just say that might make it looks cluttered, thus that is scrapped. Sorry for the disappointment over your theory.
As that last part in True Ending
Frederone gains momentum from the fall when the hydra lost its grasp on him. That, and with the heart Krotus' main weakness, he is able to stab in a knife even with his left hand.
As for the priest
Rael himself was a remarkable hero in the Northern. Thus when he was branded heretic, how will anyone involved not recognize the very son of the heretic?
As for killing
Frederone killed Hawketh not for his loyalty over Krotus, but more to his lost belief in humanity. Rosetta, Hawketh and Metheus are the only human recognized by Frederone(And thus with a different treatment). But when Rosetta killed herself, Frederone was pretty much tornt. Hawketh's claim only widens the torn.
And to answer your last post
For gaining power, it's possible, but I doubt I want to dwell on it more. This is no shounen jump manga to say least. Black magic practitioners exist, but any potent is eliminated, just like when Rael was executed. It is those cultist who claim Frederone as their god. So no, he cannot create anything except for more undeads.
Thanks for playing and the questions.