One way is to focus on Danny's emotional journey. Show his initial shock and disbelief. For example, he might find it hard to accept that his parents, who were always so full of life in their ghost - hunting adventures, are suddenly gone. This could lead to him feeling isolated as he tries to deal with this loss on his own.
The plot could involve a villain who specifically targeted Danny's parents to get to Danny. After their death, Danny is filled with anger and a thirst for revenge. He has to balance this new - found rage with his responsibilities as a half - ghost and as a son who wants to honor his parents' memory by protecting the town they loved.
Danny might react with panic at first. After all, he has been hiding his identity from his parents for so long. He could try to escape from them, using his ghost powers in a desperate attempt to get away before they can do anything drastic.
One idea could be exploring how Danny's parents react when they finally discover his ghost - hunting powers are actually related to his own ghostly nature. Maybe they initially feel betrayed but then come to accept it.
In some fanfictions, Danny Phantom may hate his parents because they are constantly trying to hunt him down. His parents are ghost hunters and they don't know that Danny is actually half - ghost. So their actions of trying to capture and study ghosts put Danny in a dangerous and uncomfortable position, which could lead to feelings of hatred.
One motive could be to get leverage over Danny. By holding his parents hostage, Vlad can try to force Danny to do things for him, like joining him or handing over his ghost powers.
Sam and Tucker would definitely be his top allies. They've been with Danny through his whole journey as a half - ghost, and they'd support him in his new role as the Master of Death. Sam could offer her unique perspective on the moral and ethical side of things, while Tucker could use his tech skills to help Danny understand any new powers or situations related to his new title.
Isolation can also be a theme. Danny may feel alone on his death day, as it's a very personal and strange experience for him. His friends may not fully understand what he's going through, so he has to deal with his emotions by himself at times. Additionally, the theme of power growth can be present. His connection to the Ghost Zone might be stronger on his death day, leading to new abilities or challenges related to his powers.
A good start could be to write a short scene that showcases the relationship between Danny's parents. It could be a simple conversation at the dinner table where they discuss their latest ghost - hunting theories. This will help you get into their mindset and from there, you can start building a larger story around them. You can also do some research on fan theories related to Danny Phantom's parents to get more inspiration.
Well, in some versions, Danny might use his ghost powers to track Vlad's lair. He could turn invisible and sneak in, then overpower Vlad using his unique abilities like intangibility and ectoblasts to free his parents.