Well, a common theme is the relationship dynamic. The overprotective mom can create a lot of comical situations in the story. For example, she might overreact to Ash's smallest scrapes or bruises. Another theme is how Ash's friends interact with his overprotective mom. Sometimes they might be amused, other times they might try to help Ash deal with her. Also, there can be a theme of sacrifice, where the mom has to learn to let go a bit for Ash's own good.
One common theme is Ash's friends being overly cautious about his battles. For example, they might try to stop him from taking on tough opponents because they fear he'll get hurt. Another theme could be his Pokémon being overprotective. Pikachu might zap anyone who gets too close to Ash in a threatening way. Also, there could be a theme of rivals becoming overprotective in a strange way, like not wanting Ash to face certain challenges as they secretly respect his skills.
There are many out there. In some fanfictions, Ash's overprotective mom might try to stop him from going on his Pokemon journey altogether. Others might have her constantly worrying and sending care packages or even trying to follow him secretly. You can also try searching on FanFiction.net for more stories about Ash and his overprotective mom.
One common theme is maternal love. Ash's mom is always shown to care deeply for him. Another theme is the home - a place Ash returns to and where his mom provides comfort. Also, there's the theme of support, as his mom is often depicted as being his biggest supporter in his pokemon - catching and battling adventures.
One common theme is friendship. Percy's overprotectiveness often stems from his deep love for his friends. For example, he doesn't want to see them get hurt during battles or dangerous quests.
Another theme is Hermione's strength. Despite her friends being overprotective, she still manages to assert herself and show her own capabilities. It's a balance between their protectiveness and her independence.
One common situation is restricting the child's movement. For example, not allowing them to go to certain places alone like parks or friends' houses.
Another theme could be Tails' growth. In some fanfictions, his overprotective nature might be a sign of his maturing. He realizes the dangers that Sonic faces and tries to be more proactive in protecting him. This can also lead to Tails developing new skills or strategies in the stories. For example, he might study more about Sonic's enemies to better protect him. And this growth theme can be intertwined with the overall plot of the Sonic universe in the fanfiction.
One common theme is loyalty. The overprotective sister is often extremely loyal to her sibling, willing to go to great lengths to keep them safe. For example, she might put herself in danger without hesitation.
One common theme is friendship. Percy's overprotectiveness can be seen as an extreme form of his friendship with Nico. He wants to keep Nico safe from the various threats in their world, which shows how much he values their bond.
The theme of family loyalty often shows up. Thor feels it's his duty to protect Loki because they are family. Also, the power dynamics in Asgard can be a theme. Thor's overprotectiveness can be influenced by his position of power and his need to keep Loki, who is sometimes seen as a bit of a wild card, in check.