These notes need to be made for my reference and a clearer explanation of the way I play Seth.
First note is on her self-isolation:
For the better part of 900 years Seth has distanced herself from everyone around her for the better part of those nine centuries.
To start with, she's never entirely alone. She does have favorites and she does dress as Seth and make friends amongst others as well. But she's never been able to really connect with anyone beyond a shallow level. Trust, adoration, friendship, all of it can still be shallow. Seth keeps the truth of everything locked away very deeply.
Reasons:
1: A form of self-punishment. In the war Seth fought not only against Terrans, but Lilith who was like a mother to her. She would like to say that she stopped fighting immediately once Lilith took a side, but she didn't. She feels that if she had taken a stand earlier against Cain she could have prevented Lilith's death. She takes her fair share of the guilt around Lilith's death and Cain's own descent into madness. Thus, her loneliness is vaguely self-inflicted.
2: Fear of the truth being let out. Seth does view Crusniks as almost being monsters. Especially with what they've done in the past. And she's afraid of letting the others see that side of her. Even if only by accident. At one point, she bonds with a squirrel she calls Abel. But when she releases her Crusnik the squirrel fears her and runs, and she only smiles as she realizes she's alone again. She doesn't think she can be loved if the truth is let out about her Crusnik abilities. This also explains her veiling herself from being seen and the false name.
3: Her long life. It also makes it painful to bond with people when they won't live as long as her and she'll lose them one day. With Abel she knows they'll be living forever together. But with the Methuselahs they only live to be about 300. It's easier than loving and losing them.
Next note is on her reasons for being Empress/what she does as Empress:
For 900 years Seth has ruled as Empress Augusta Vradica. In this time she has championed peace and coexistence between the Methuselah and the Terrans.
Reasons:
1: For Lilith. Yes, I know most people believe that Seth hasn't declared war because her brother's place in the Vatican, but I have counter thoughts to this. Abel did reside in the Vatican for 900 years, but not as their supporter. Rather he was their to stay with Lilith in her tomb and mourn losing her. He technically didn't join up with the Vatican until around the time that Caterina entered his life. Which is why I find it strange that Seth didn't declare war on the outsiders when technically Abel was too incapacitated to have really even chosen a side yet.
Which is where my next line of thinking comes into play that this is partly for Lilith. Lilith did want peace for the land and Seth owes it to her to give her this much.
2: Her original desires in the war. It's believed that originally Abel fought because he disliked humans, Cain because was driven to destruction by Crusnik, and Seth for domination. I believe that in a way, Seth didn't give up that idea, only altered it to better the world. I also don't think it's in her mind to really dominate and control, but now guide and direct them to coexistence and peace.
Final note on Crusnik and Bacillus differences:
1 UV Rays: Just my own general thoughts about this really. The Bacillus is a different strain from the Crusnik developed to aid the Martians who were further from the sun than Earth. Which is why when they come to Earth the nanomachines react badly to the sun's proximity and eat at them from the inside. But as the Crusnik is from god only knows and made its way to Mars, then it doesn't really react to an even closer proximity to the sun and 'spazz out' like the Bacillus does. That's why I think that Crusniks are not affected by sunlight like the Methuselah are.
2: On Feeding: I don't think it's entirely necessary for them to feed on Methuselah. At least not often and especially when not using the Crusnik. Seth has starved herself for 900 years and refuses to feed on her children. Yet she still lives normally, and even used her Crusnik at least once in this lifetime. Leading me to believe it's not entirely needed when Crusnik is contained. But this is speculation as Seth's 900 years are mostly a mystery when it comes to the details of her private life and their frequency of feeding isn't addressed elsewhere.
Other notes added as I think of them:
On Cain: Cain is her older brother. Seth is the one who injected him with the Crusnik when he nearly died before without proper knowledge of what the Crusnik's effects on humans would be. Seth carries a lot of pain on this subject, and basically blames herself for her brother's insanity and for him killing Lilith sometimes.
On personality: No. Seth will never angst. Not publicly at least. Maybe anonly if she can get away with it. But Seth has a lot of pent up pain and suffering and loneliness. Hell, even Able doesn't fully understand how much she still suffers. Seth can be serious, she can be sad, but never angsty. And if you see her sad, you might catch a glimpse of pain beyond that that dwells deeper than what you first expect. But don't expect her to linger or elaborate. Seth is very closed off that way.
Resources: Look at this pretty
link Setine found for me~ So helpful for Seth notes too.