Well, in scp death note crossover fanfiction, a cool concept is the clash of different power systems. The SCP entities have their own unique and often bizarre abilities, and when combined with the Death Note's ability to kill just by writing a name, it creates a really chaotic and interesting scenario. Maybe some SCPs would try to find a way to nullify the Death Note's power or use it to their own advantage in their never - ending pursuit of chaos or control.
In such fanfiction, an interesting aspect is the character interactions. Imagine an SCP researcher finding the Death Note and trying to study it while also being tempted by its power. Or perhaps an SCP that has some form of mind - control ability using the Death Note to expand its influence. There could also be a scenario where SCPs and the characters from Death Note form an uneasy alliance against a common threat, which would be really fascinating to explore.
Well, in 'kaneki crossover death note fanfiction', a possible concept is the way their different worlds collide. Kaneki comes from a world full of ghouls and the CCG, and Light is in a world where he's using the Death Note to change society. If they were to meet, it could lead to some really intense power struggles. Also, the idea of how their respective allies and enemies would react to the crossover is quite fascinating. Kaneki's friends from Anteiku might be completely bewildered by the Death Note, and Light's accomplices might see Kaneki as a new threat or a potential tool.
I think the Task Force members from Death Note could be involved in scp death note crossover fanfiction. They were always in the middle of the chaos caused by Light and the Death Note. In the SCP world, they would have to deal with not only Light but also the various SCP threats. Also, SCP - 105 could be an interesting addition. Her ability to interact with photographs could potentially be used in relation to the Death Note. Maybe she could take pictures of the names written in the Death Note and use it in some strange way.
A cool crossover idea is if the Shinigami from the Death Note world are interested in the chakra system in Naruto. They might make deals with ninjas, offering them the power of the Death Note in exchange for their chakra or some other valuable things. And also, imagine if Sasuke from Naruto was in the Death Note world. His desire for power and revenge could be redirected in a different way with the existence of the Death Note. He might see it as a tool to take down his enemies more efficiently.
One interesting concept could be Naruto getting his hands on the Death Note. Imagine how his ninja values would conflict with the power of the Death Note. He might be tempted to use it for what he believes is justice in the ninja world, but his sense of right and wrong within his own moral code would be put to the test.
One interesting concept is the various SCP objects themselves. In fanfiction, they can be explored in more depth, like the strange abilities or backstories of the SCPs. For example, SCP - 049, the Plague Doctor. Fanfictions might delve into how it came to be and what its true motives are. Another concept is the Foundation's internal politics and how different personnel interact. There could be stories about researchers trying to gain more power within the Foundation or ethical dilemmas they face when dealing with the SCPs.
A crossover with 'Fullmetal Alchemist' could also be fascinating. Maybe Edward Elric discovers the Death Note in his search for the Philosopher's Stone. He would be conflicted because his moral code as an alchemist goes against using such a tool for killing, yet the power it offers could potentially help him achieve his goals in a different way.
One possible plot could be that Light Yagami discovers the existence of demons from the Inuyasha world. He might see them as a new type of 'evil' to be eradicated. He could start using the Death Note on demons, which would draw the attention of Inuyasha and his group. Inuyasha would initially be confused about these strange deaths and then realize that a human is causing them. This would lead to a conflict as Inuyasha believes in slaying demons in a more 'honorable' way and not through this strange notebook's power.
Well, perhaps a concept is the power dynamics. If Harry is death in this crossover, he would likely have a great deal of power. In Kuroshitsuji, power is a major theme, especially with Sebastian's demonic powers. Harry's power as death could either clash or complement Sebastian's. This could lead to some really intense and unique storylines where the characters are forced to navigate around these two powerful forces.
If Naruto got the Death Note, it would be a complete chaos. Naruto has a strong sense of justice, but his understanding of it is very different from Light's in Death Note. He might initially be horrified by the power of the Death Note and try to destroy it. However, if he decided to use it, he could potentially target powerful enemies like Orochimaru or Pain without having to engage in direct combat. But this would also corrupt his ninja way as killing without a fair fight goes against his beliefs. He would likely struggle with the moral implications throughout the story.
One interesting concept could be how Harry Potter's new role as the master of death changes the power dynamics in the wizarding world. For example, it might make him more feared or respected by other wizards.