One possible plot development could be Naruto using his newfound magic in combat. He might combine his ninja skills with magic spells, creating unique and powerful attacks. For example, he could use shadow clones and then have each clone cast a different magic spell, overwhelming his enemies.
Naruto would likely become more confident. With magic at his disposal, he would have new tools to face challenges. His already strong will would be further enhanced as he masters the magic, knowing he has more power to protect his loved ones.
One unique plot element could be Naruto's struggle to adapt to the new magic system. He's used to chakra, but now has to deal with a whole different kind of power. This could lead to some really interesting training arcs where he has to learn magic from scratch, making mistakes along the way and slowly mastering it. It might also involve his friends not understanding this new power he has, causing some tension in their relationships.
Naruto's character develops by becoming more adaptable. He starts out confused and a bit frustrated with this new magic concept. But as he progresses, he learns to be more open - minded. He realizes that there are different ways to be strong other than just relying on his ninja abilities. This makes him more well - rounded as a character.
Well, the plot could involve Naruto discovering this take over magic during one of his adventures. Maybe he finds an ancient scroll that teaches him this magic. He then uses it to take over the powers of his enemies in battles, like he takes over the sharingan ability from Sasuke for a short time to gain an edge in a fight against a powerful foe.
His character would become more versatile. With the take over magic, he would have to learn to be more strategic. Instead of just relying on his normal jutsu, he'd be thinking about which powers to take over in different situations. This would make him a more calculating and less impulsive fighter.
One possible consequence is that Naruto might lose control of his own actions. The Kyuubi is a powerful and often uncontrollable force. So, he could end up causing a great deal of destruction without meaning to. For example, he might attack his friends or allies in the heat of the moment as the Kyuubi's power overwhelms his own judgment.
Maybe it could be due to some dark jutsu he discovers accidentally. For example, he might find an ancient scroll in a hidden cave that details the method of controlling corpses. This could be a jutsu forgotten by time, and Naruto, being the curious and determined ninja he is, decides to study it.
Yes, there are quite a few. You can check out fanfiction websites like FanFiction.net or Archive of Our Own. Some stories might explore Naruto's newfound soul magic abilities in relation to his existing ninja skills, like how it could enhance his Rasengan or his shadow clone jutsu.