Marina was not the only troublemaker to be got rid of as over the centuries various beings who asked awkward questions ended up dead in a variety of ways. This was why Brankaresh was so hopeful Eileen would get her comeuppance without him necessarily having to do anything about it. He forgot in Eileen’s being out and about, talking to people, getting rid of obvious threats such as dragons and trolls, she was enormously popular. This gave Queen and Council a dilemma too. There was a limit as to how far they could rein Eileen in, given they didn’t want to upset the populace either.
Marina and Eileen come from a very long line of noble royal fighters. Part of the reason the royals bagged the throne was they led the defence of the realm when it was being attacked by outside forces and it was felt giving them the crown was an appropriate way of thanking them. Eileen certainly believes it’s become a bit of a curse and has no wish to inherit it herself. Jennifer was horrified to learn she wasn’t just half fairy but half royal fairy. She got out of dressing up in a posh frock and a crown when she was a kid.