I don't think the jester represented Fate. Jillian is still fated to become Queen of Faq, and fulfills that Fate. I also am not feeling the ties between the jester and free-will or Duty. I can more readily accept the attunement, which would make for Charlie either cornering the market on Tools, or he has experienced the negative aspect of Attuning and wants to prevent it from happening again. It's also easily explained as to why he didn't perform the same surgery on Wanda -- she had not been Fated to Attune yet... she doesn't get that Fate or knowledge of such until both her and Marie are back in Faq.
Other things to consider between this update and book 1. It helps explain why she thought of herself as Jillian Zamussels instead of Jillian Banhammer. The Banhammer aspect had been removed. It also adds to her story of one morning she was a mercenary warlord for Faq, the next morning she woke up in the field as a Barbarian. Her armour style was completely different, no longer her father's oriental inspired designs. her rations no longer pop as sushi and/or rice All of the disconnects between Book 0 Jillian and Book 1 Jillian are within that Jester, whatever he is.
Faq, as a Side, shouldn't have fallen since it had an heir at the time the Ruler croaked. Jillian should have auto-promoted to Ruler and she should have been able to re-found the cities within Faq and rebuilt them. Something about her heir mechanism broke. She remembers Faq units, knows Wanda and Jack by name, so she didn't get a complete mind wipe of her association with Faq. She still retained her Royal status, and the Summer Updates showed us that she still retained her etiquette, though she loathed using it.
If anything the Jester could represent the concept of family, or the influence family has on personality. Regular units don't have parents and no familial identity, so there'd be no way for Betsy to know what that was, though Charlie definitely would know. During the smoke screen incident, the Jester manifested in the last known location of Banhammer. Jillian's biggest opponent was never out in the field, where she was free to be who she was, but back home in her father's stuffy court. She never has any problem handling the harsh life out in the field, of being uncomfortable, of enduring bad weather, of constant combat, or of any of the harshness of her reality as a mercenary. What she has a severe problem with is her father's stuffy court, her father's rules, her father's pacifism, and her father's expectations of her. In her flower dreams, the jester was impotent and obnoxious, much how Banhammer's influence on her activities actually were. Actually inside of her head, the jester wielded a lot more power than she wanted to admit.
Charlie is no stranger to battling against family. He has shown absolutely no remorse of hard feelings towards the woman who murdered his daughter; in fact, he later goes on to bank-roll said murderer. Somehow Charlie was able to sever his ties to his own family, and that was probably about the same time he withdrew and stopped pursuing warfare.
Just musing. A lot to ponder in this one.