Obviously, Danny is a central character even though he dies young. His family members are often important characters too, like his parents and siblings. They are usually shown dealing with the aftermath of his death. His friends also play a significant role. They might be the ones who knew Danny the best in his short life and could have interesting stories and memories to share. Sometimes, there could be a mentor - like figure who knew Danny and tries to guide others in the wake of his death.
One common theme could be grief. Since Danny dies young, other characters in the fanfiction might have to deal with the intense sorrow of losing him prematurely. Another theme could be the idea of unfulfilled potential. Danny might have had dreams or talents that were cut short, and the story could explore how those around him remember or try to honor that. There could also be themes of regret, like if someone had an argument with Danny before he died and now has to live with that guilt.
One aspect of 'ichigo dies young fanfiction' could be the impact on the overall plot. If Ichigo dies young, it can completely change the direction of the story. Maybe new characters rise to fill the void he left, or existing characters have to take on new roles. It also allows for a different exploration of the themes in the original work, such as the fragility of life and the importance of friendship in the face of loss.
One popular 'Danny Phantom Danny Dies' fanfiction might be 'The Aftermath'. In this type of fanfiction, the story often explores how the other characters deal with Danny's death. For example, Sam and Tucker may go through a period of extreme grief and guilt, wondering if they could have done something to prevent it. Another could be 'A World Without Danny', where the entire Amity Park starts to change in unexpected ways due to Danny's absence, showing how much of an impact he had on the town.
One possible storyline could be that Danny sacrifices himself to save the world from a powerful and evil ghost. Maybe he uses all his energy in a final battle and fades away, leaving his friends and family to mourn. Another could be that he's tricked by a villain into a death - trap that he can't escape from.
A new and powerful ghost that Danny has never faced before could be the main antagonist. This ghost could have unique powers that Danny isn't prepared for, and in their first encounter, it manages to defeat and kill Danny. This would set the stage for a story of revenge or trying to bring Danny back.
Often, they end on a bittersweet note. For example, the town may have finally found peace after Danny's sacrifice, but his friends and family are still mourning his loss. His friends might vow to carry on his mission in his memory, which gives a sense of hope among the sadness.
In many Young Justice fanfictions where Batman dies, it often leads to a major shift in the dynamics of the team. The younger heroes would be forced to grow up even faster. For example, Robin might take on a more serious and leadership - like role. He would have to deal with not only his own grief but also the responsibility of guiding the team in Batman's absence. It could also lead to some heroes doubting their abilities without Batman's strategic mind behind them.
Grief is a very common theme. Since Ichigo's death is unexpected and early, the other characters are likely to experience deep sorrow. Another theme could be the search for meaning. After his death, the remaining characters may start to question their own lives and what they are fighting for.
One great 'Young Justice Danny Phantom' fanfic is 'Phantom in Gotham'. It has an interesting plot where Danny's ghostly abilities interact with the Young Justice team in Gotham city. Another is 'Danny's New Allies' which focuses on how Danny teams up with the members of Young Justice and the dynamics between them.