It can create a sense of suspense. The other characters will be worried about him and the readers will be eager to know what will happen next. For example, if Ladybug sees him motionless, she'll try to figure out what's wrong and how to help him, which drives the plot forward as she investigates.
It could also be due to a spell or an akuma's special ability. In the Miraculous universe, there are many powers that can immobilize characters. For example, if an akuma had the power to paralyze people, Adrien might have been caught in it. And since he's often in the middle of the action, he'd be a prime target. He might be motionless as his body is fighting off the effects of this external force, trying to break free from it so he can transform into Chat Noir and save the day.
Well, it could be that he's been injured in a battle against an akuma. Maybe the akuma had a particularly powerful attack that left him unconscious and motionless.
A great fanfiction idea could be that Adrien and Kagami are paired up for a school project. As they work on it, they start to realize that they have more in common than they thought. They could share their dreams and fears, and this new - found closeness might make Adrien question his feelings for Ladybug a bit more.
I really like 'Adrien's Discovery'. In this fanfiction, Adrien starts to notice Marinette in a new light. He begins to see all the little things she does for him and how selfless she is. It has some really heart - warming moments, like when Adrien defends Marinette from Chloe's mean remarks. It's a great read if you want to see more of Adrien realizing his feelings for Marinette.
This fanfiction could be about many things related to an unresponsive Adrien in the Miraculous world. It might explore how his lack of response affects the other characters. For instance, if Adrien is unresponsive, it could make Marinette worried and she might try to find out what's wrong with him. The story could also be about how his unresponsiveness impacts the overall plot, like if he's unresponsive during a key moment in the fight against Hawkmoth, it could lead to some big changes in the story's direction. It could also be a character - study type of fanfiction, delving into Adrien's psyche when he's in this unresponsive state.
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.
One possible story could be that Adrien gets akumatized because he feels constantly overshadowed by Ladybug. In this fanfiction, Hawkmoth might prey on his insecurities. As an akumatized form, Adrien could have enhanced physical abilities like super strength and speed. His akumatized look might be a dark version of his Chat Noir costume, with a more menacing appearance.
There are many interesting fanfictions out there about Adrien's car in Miraculous Ladybug. Some might focus on Adrien using his car to go on secret adventures while being Chat Noir. For example, he could use the car to quickly reach a location where an akuma attack is about to happen. The car could also be a place where he has some private moments to think about his double life and his feelings for Ladybug.