It could be that the 'blackness' is a curse or some sort of negative energy that's afflicting Adrien, thus causing him pain. For example, it might be a magic - based affliction that saps his strength and causes him physical and mental pain.
The 'blackness' might represent a part of Adrien's past that he's ashamed of or a trauma. This could be related to his family, perhaps something his father did or a family secret. And this 'blackness' from his past keeps resurfacing in his mind, causing him great pain as he tries to deal with his present life as a superhero or a normal teenager.
In Miraculous fanfic, if we consider 'blackness' as a symbol of the unknown or the feared, it can be linked to Adrien's pain. He may be afraid of this 'blackness' within him, not understanding what it is or how to control it. This fear and confusion can be a source of pain, like an internal struggle that's constantly nagging at him and affecting his daily life and relationships.
In Miraculous fanfics, the concept of Adrien and pain often goes hand - in - hand. If 'blackness' is introduced, it could be a symbol of something negative that's causing him pain. It might be a dark power that he's trying to resist, or it could be emotional pain from a past event that's now resurfacing and is symbolized by this 'blackness'.
This event in the fanfic could also lead to new characters emerging. Maybe someone would try to take on Ladybug's mantle in a different way. Or new villains could rise, seeing the opportunity in the chaos. The magic of the Miraculous might be affected too. Since Ladybug was an important part of the magical balance, her death could have unforeseen consequences on the powers and the Miraculous themselves.
If Adrien is in the hospital, it could create a sense of urgency for Ladybug. She might be more determined than ever to defeat the villains on her own, as she doesn't have her partner by her side. This could lead to her making some risky decisions in battles. Also, she would probably be worried about Adrien's well - being, which could affect her focus during normal life situations as well.
There's a fanfic called 'Female Adrien's Adventure'. It's set in an alternate universe where Adrien is female. The story focuses on her as a Miraculous holder and how she copes with the responsibilities. It has some really cool action scenes and also some sweet moments where she interacts with her friends. It's a must - read if you like this concept.
In a fanfic, Adrien might collapse injured because of some sort of curse or negative magic. For example, a new villain discovers a way to target the Miraculous holders directly. Adrien, being Cat Noir, is affected and his powers start to backfire on him, causing him to collapse. His partner, Ladybug, then has to figure out how to break the curse and save him.
Then, show his unresponsiveness through the reactions of other characters. If Ladybug tries to talk to him and he doesn't answer or even blink, it emphasizes his state. You can also use dialogue from the other characters to express their concern and confusion about Adrien's unresponsiveness.
These fanfictions usually show Adrien with a lot of flaws. He might be painted as being manipulative, using his charm to get what he wants without considering the feelings of those around him. Sometimes, he is shown as being irresponsible, not taking his role as a superhero seriously enough. They really dig into the idea that he is not as perfect as he seems in the original series. They may also show him as being overly jealous, which can cause problems in his relationships. For instance, if he is jealous of another character getting close to Ladybug, he might act out in a negative way.
A good fanfic in this case often has strong character development. For example, the female Adrien should have a distinct personality that still retains some of the charm of the original character. It should also have an engaging plot. Maybe she has to face different challenges because of her gender in this new version.
One possible plot could be that Adrien gets hit by a villain's special power that makes him go limp. His friends in the Miraculous team then have to find a way to reverse the effect while protecting Paris from other threats. Maybe Ladybug has to use her creativity to come up with a new power - up or a new strategy to save him.
It can create a sense of urgency. Other characters will then be focused on helping him recover. Ladybug, for instance, might be more determined than ever to defeat the villain responsible. It can also lead to character development for Adrien. He might have to face his own vulnerability and learn to rely on others more while he's injured.