Unfortunately, yes. Though they've both been known to make threats like that rather lightly [Anise's "I'll kill you bastards!" comes to mind, alongside Arietta's tendency to threaten to kill anyone who wrongs her -- though the seriousness in both circumstances could go either way.] I'm not entirely convinced that either of them wouldn't jump at the chance if a fight were to break out between them.

[Which was never a question with Arietta -- but that last conversation with Anise struck an unpleasant chord in him. It's true they were enemies back home, but there's a difference between doing what's necessary to save the world and killing for the sake of killing.]