(Had Xander gone, gods forbid, would Camilla have taken the throne in his place?)
Camilla would never really want the throne. The only way she’d ever step up to the plate would be via the death of all the rest of her siblings, and even then, that’d be a special circumstance - she’d be on the front lines to defend them and her home, because she’ll defend her family and those she loves until her last breath. If she’s alive and without them, well…
It would never make her happy to become Queen - leading so many people and being under constant public scrutiny would make her continually anxious, and she doesn’t enjoy paperwork either. She wants to make a home she never had, and be able to love her own children as she was never loved in her youth, and be able to raise them away from the constant infighting of Nohr. She has to be in control of things in her purview, so I think a country is too large and always out of control.
Each of the Nohr Sibs has a role - and it may seem on the surface that she’d be good at looking after people owing to her motherly personality, but her biggest enemy is actually herself. She’d destroy herself with self-doubt when put in the public eye until she couldn’t take it any more. She constantly fears being left alone and unwanted, and has trouble trusting those outside of her very tight social circle.
Camilla is very severe and scared of loss. The softness, the alluring way she talks is something she’s cultivated to make people love her. On the battlefield, she revels in her role as a fearsome, unrelenting opponent, an experienced warrior with accolades and a reputation as a merciless monster to her enemies. She’s proud of that, too.
It’s also interesting if you look at Camilla’s retainers as reflections of herself:
Selena was always striving to reach her mother’s high standards, she’s antagonistic and rather bitter, and she prides herself on her looks and her style. She’s a woman of class, despite not being a titled lady. But she’s loyal, and once you’ve got her in your confidence, she’s kind. Her attitude is a product of her environment.
Beruka, on the other hand, is a girl made into a weapon. She grew up deprived of many things, made ready to kill from very early in her youth. She struggles to understand the emotions of others and has trouble divorcing her job from her reason to live. But even then… She’s very caring, and there’s a very sweet and devoted core to her.
So Camilla wouldn’t want to take the throne, no. It’s not in her nature. She might try, but she’d be a wreck without Xander around and if Leo was alive he’d make a much better leader, so she’d abdicate in his favour. He’s a much better and more meticulous planner, and he doesn’t let his feelings colour his actions like Camilla does.
