Princess Serenity and Prince Endymion, why exactly did you NEED guardians before the end of the Silver Millennium? We know that up until the very end, things were peaceful, so what need was there for guards?
Well, isn’t it common for royalty to have guards and be protected? Our parents just wanted us to be safe.
We were the heirs of the throne, after all. And even though that time was more peaceful, it didn’t mean there was zero conflict. Absolute peace or utopia is impossible. Conflict will always be present.
Serenity Hatake is the daughter Kakashi Hatake (obviously), but he never knew he had a daughter. Serenity grew up an orphan (much like Naruto) and she continued to strive to be a great kunoichi. Once Serenity reached the level of
Jōnin Kakashi took an interest in her. It wasn’t until Serenity mentioned her past that Kakashi had realized he finally had a family.