One possible motive could be fear. Ichigo is extremely powerful, and they might fear that he could one day turn against the Soul Society. So, to prevent any potential future threat, they order his death.
Maybe it's a matter of politics. There could be factions within the Central 46 that see Ichigo as an obstacle to their plans. For instance, if there are groups within the Soul Society that want to change the current power structure and Ichigo is seen as a symbol of the old or new order, depending on how you look at it, they would want him out of the way.
Another motive could be misinformation. The Central 46 might have been fed false information about Ichigo. They could think that he has committed some heinous crime against the Soul Society when in fact he's innocent. This would lead them to order his death based on false pretenses.
I'm not sure which specific 'Central 46 Orders Ichigo's Death' fan fiction you are referring to. There could be many different interpretations and stories out there. It might be a very dark and alternative take on the Bleach universe where the Central 46, which is an important governing body in the series, orders Ichigo's death for some reason. Maybe it's because they see him as a threat to their power or their view of how the Soul Society should be maintained.
Aizen might be motivated by power. Ichigo has a very unique power set that Aizen may want to harness for himself. And Rukia, being from Soul Society, could be used as a way to gain information or leverage against Soul Society.
It could lead to some really interesting plot twists. Ichigo's powers and nature might interact with the Espada's dynamics in unexpected ways, creating a whole new story arc.
Maybe he wants to use Ichigo as a bargaining chip. If there are other forces or characters in the fanfiction world that Kisshu is in conflict with, he could kidnap Ichigo to gain an advantage over them. For example, if there are rival groups vying for power or resources, Ichigo might be valuable to them in some way, and Kisshu could use her to negotiate. Another motive could be that he believes Ichigo has some sort of special power or knowledge that he wants to extract from her, and kidnapping is his way of getting close enough to do so.
One possible motive could be a deep - seated dissatisfaction with the wizarding world's status quo. Maybe she felt that the Ministry of Magic was corrupt and that the Death Eaters had a better vision for change, although a very dark one. Another could be some sort of personal vendetta against someone in the Order of the Phoenix or Hogwarts faculty that made her side with the Death Eaters.
Well, it could be about Ib getting lost in a strange and dangerous world, and the Angel of Death is either her guide or her pursuer. Maybe they form an unexpected bond as Ib tries to find her way out of the nightmare - like place.
Maybe it could involve Naruto sacrificing himself to save the village from an ultimate evil. For example, a new and extremely powerful enemy emerges that is immune to all known jutsus except for a forbidden one that Naruto has to use, but it costs him his life.
Jealousy could be a motive. Maybe another woman in the social circle was envious of Eliza's status and relationship with Alexander Hamilton, so she plots her death. It could also be for political gain. If there were people who wanted to undermine Alexander's influence, they might think that killing Eliza would break him and make him less effective in his political pursuits.
In some cases, it could be the environment itself. For instance, if they are in a highly dangerous and unforgiving area, like a collapsing building or a toxic zone, and Ellis makes a wrong move trying to lead the group through, which leads to his death.
Well, it could be about a customer in a magical story - ordering store. The customer wants a story with a brave knight, a dragon, and a princess. The clerk then starts pulling out different 'story ingredients' like a magical sword for the knight and a fire - breathing spell for the dragon. And finally, they package up this wild adventure story for the customer to take home and enjoy.