The main character might be a politician. In the dark world of politics filled with greed for power and influence, this politician is no different. But then, a chance encounter with a group of idealistic activists could be the 'light in the dark' that starts to change their perspective.
It could be a wealthy businessperson who has become blinded by greed in the cut - throat corporate world. They are the main character and the 'light in the dark' could be a poor but wise employee who shows them the error of their ways.
Maybe it's a powerful wizard in a fantasy setting. The wizard has been corrupted by greed for more magical power. And the 'light' could be a young apprentice who has a pure heart and through their innocence, makes the wizard reevaluate his actions.
Well, it could be about a character who is consumed by greed in a dark world. Maybe they find a glimmer of hope or a 'light' that makes them question their greedy ways. For example, they might meet a selfless person who shows them there's more to life than material gain.
A brooding vampire could be the main character. He has lived for centuries and has seen the worst of humanity. However, he decides to use his superhuman strength and speed to protect a small town from other supernatural threats that lurk in the night.
A young orphan could be the main character. They are lured into the dark woods circus by the promise of a family and a place to belong. But soon they realize the dark secrets of the circus.
Sasuke could also be a main character in such a fanfiction. Given his brooding nature and his search for power, the addition of dark angel powers could take his character in an even more complex direction. He might be more tempted by the dark side that comes with the dark angel powers.
Perhaps a young and inexperienced adventurer who discovers their hidden power while on the quest to slay the dark dragon. They grow throughout the story, learning new skills and becoming a true hero.
Harry Potter himself could be the main character. Imagine him stumbling upon a dark keyblade and having to grapple with its power. He would have to decide whether to use it to fight Voldemort or risk being corrupted by its dark influence.
The main character could be a young artist. She is inspired by the night and the solitude it offers. The darkness is like a blank canvas for her, and dancing is her way of creating art. Every movement she makes in the dark is a form of self - expression, and she might be on a journey to find her true artistic identity through her love for dancing in the dark.
I'm not certain about all the main characters in 'Re Zero Greed if Light Novel'. However, in the broader Re Zero universe, Subaru is central. He's the character through which we experience the story. Emilia is also very important as she has a claim to the throne in the fantasy world and is a love interest for Subaru. In this 'Greed if' version, there could be new characters related to the theme of greed. Maybe there's a powerful mage who is extremely greedy for magical knowledge or a noble who is greedy for land and power. But without more information, it's hard to say for sure.
It's hard to say without reading it specifically, but it could be Naruto himself dealing with the concept of greed in some way. Maybe he has to face an enemy who is extremely greedy and he has to find a way to stop them without succumbing to the same sin.
A powerful mage could be a great main character. They could use their magic to either combat the Four Kings or try to understand the source of their corruption. Magic in the Dark Souls world is often mysterious and having a mage as the main character could allow for exploration of different spells and magical concepts in relation to the Four Kings.