It occurs to me that I should probably talk about Emil, his two personalities, and how I'm playing them in Micro/CFUD. This essay contains spoilers for the whole game, including the Normal and Perfect endings. There is also much tl;dr and two diagrams. You have been warned!
PREGAME RATATOSK
Okay, so, once upon a time there was a Summon Spirit named Ratatosk. He was a pretty important guy! Before the original World Tree withered, he was the spirit charged with taking care of it. In addition to that, he was also the Lord of Monsters, using his servants the Centurions to form contracts with monsters and regulate the flow of Mana. Most importantly to the game's plot, though, he protected the gate to Niflheim, the world of the demons. Well, roughly 4002 years ago, shit went down involving the Great Hero Mithos, who split the world in two to stop a war. Without getting into too many details, Mithos had to come up with a crazy system to alternate mana expenditure between the two words, since there was only enough for one at a time. This was a problem for Ratatosk, because he, you know, regulated the flow of mana. As a result of this and the destruction of his World Tree, Ratatosk got very pissed off, decided he hated humans and half-elves, and went to sleep for a long, long time.
Cue two years pre-game. The heroes of the first game reunite the two worlds. All is happy, yaaay! Except for the part where, now that the worlds are merged again, the mana needs to be regulated by Ratatosk again. And he's still sulking, unaware of what's going on, and no one even knows he exists anymore, anyway. Natural disasters start plaguing the world. A brilliant young scientist named Aster hypothesizes that when the world was previously one, there was a being that handled mana and kept these disasters from happening. With the help of his friend and coworker Richter, Aster tracks down one of Ratatosk's Centurions, the water spirit Aqua, and awakens her. When she learns what's happened, she readily agrees to take them to Ratatosk in order to set the flow of mana straight again.
The only problem is, Ratatosk's still pissed. He agrees to wake the rest of the Centurions and regulate mana flow, but he also decides that a good plan of action would be to kill all humans and half-elves so that they never fuck things up again! Aster tries to reason for him, and is killed for his troubles. Unfortunately for Ratatosk (but fortunately for the human race), this upsets Richter so much that he attacks and kills Ratatosk.
Now, Ratatosk, like his Centurions, can't permanently die. "Killing" him results in him retreating into his "core," a gemlike object, and slumbering there until he is reawoken. Richter tries to destroy the core as well, but is stopped by the Centurion of Darkness, Tenebrae. Long story short, both Tenebrae and the core end up in possession of a girl named Marta. Tenebrae informs her of the need to awaken the other Centurions and eventually Ratatosk himself to save the world. He neglects to mention Ratatosk's currently homicidal mood. Marta ends up in the city of Palmacosta while it's being attacked, and calls out to Ratatosk's core for help.
THIS IS WHERE THINGS GET INTERESTING.
Ratatosk can't fully awaken because his powers haven't been returned to him. But he can and does partially awaken. Part of his core becomes affixed to Marta's forehead, where it's sustained by her body's lifeforce. The rest of Ratatosk, with this boost in energy, is able to materialize in a physical form. Subconsciously, Ratatosk seems to have been thinking of Aster, because said physical form is an exact replica of him (we have no idea what form Ratatosk took before this -- all pre-game flashbacks take place from his first-person POV). But because Ratatosk's power hasn't returned to him, he stays slumbering inside of himself, and creates a "shield" or "decoy" personality to face the world with until he can awaken, which has no memories of his true nature.
IN-GAME RATATOSK
Due to a completely random series of events, the amnesiac Ratatosk finds himself believing he's a boy named Emil Castagnier. Emil is timid, eager-to-please, gentle, and generally adorable. I mean, the boy cuts vegetables into cute animal shapes when he cooks, for crying out loud. However, as time goes on, he develops a core of strength based his desire to protect Marta, and, ironically, advice given to him by Richter. Fairly early on in the game, Emil is given a bit of Ratatosk's power back by Tenebrae.
The return of this power reveals in him a second "personality." This side to Emil, called "Ratatosk Mode" by his friends, comes out in battle -- it's coarse, angry, and bloodthirsty. Basically, "Ratatosk Mode" is closer to the original Ratatosk than "Emil" is. As more Centurions awaken, the "Emil" personality becomes weaker and less prevalent, oftentimes unaware of what's going on when the other personality is in control.
While they're like this, the two personalities seem unable to communicate with each other directly, even though they're aware of their respective existences. Emil sometimes turns to Ratatosk Mode for help in tough situations, and Ratatosk Mode disdains Emil's kindnesses as "weak."
At the end of the game, in order to restore the balance of mana to the world and reseal the gate to Niflheim, Ratatosk has to fully reawaken. Since both personalities are part of Ratatosk, this means they have to merge. OBSERVE THE PATH RATATOSK'S PERSONALITIES TAKE:
When this happens, we're back to the Ratatosk of pre-game -- only he's changed a lot, since he's been affected by the experiences both his personalities have gone through. Luckily, this results in a more mellow Ratatosk who abandons his desire to, you know, kill everyone. As Ratatosk himself puts it, he's both Emil and Ratatosk now -- which is how he's supposed to be.
RATATOSK IN MICRO/CFUD
But wait, you say! You're playing post-game Ratatosk! Why on earth are you still playing it as though he has two personalities when they merged? Well, they did merge. But not to the point where the two personalities are entirely indistinguishable. As the party leaves the gateway, it's green-eyed Emil who tells Marta he loves her. And in the Perfect ending, Ratatosk splits to allow Emil to live out a human lifespan with Marta, while the rest of him remains in the gate in core form, supported by Richter's lifeforce. So, obviously, there's still some leeway to mess around.
Basically, I think it's like a Venn Diagram. BEHOLD:
It's sort of like Emil has three personalities. He has his "true" or "real" self, the merged Ratatosk, which combines elements of the two base personalities. But he can also still split into regular Emil and the more easily-irritated and less mature version of Ratatosk. Since the personalities are more or less balanced in power (except for "true" Ratatosk, who's obviously strongest), I'm playing it as though Emil doesn't have blackouts when Ratatosk is in control anymore, sort of like it was in the earlier parts of the game. When they're split like this, it would stand to reason that the two personalities can communicate with one another if they concentrate (in that swirly space they talk in those two times in game).
And uh. Wow, that was a lot of leadup to what amounts to two paragraphs explaining my reasoning for how I'm playing Emil here. But writing this whole thing helped me get my thoughts in order, so I don't think it's a waste.