Zoro often puts himself between Luffy and danger. For example, when facing strong opponents, he'll be the first to step forward and engage, making sure Luffy is safe behind him.
Fred often uses his humor to diffuse tense situations that Hermione might be in. For example, if she's being harassed by some bullies, he'll make a joke that makes the bullies look stupid and also makes Hermione feel better.
In some fanfictions, Naruto shows his protectiveness by getting extremely angry when someone badmouths Sakura. He won't tolerate any disrespect towards her and will quickly defend her honor. He might also use his influence in the village to make sure Sakura is always safe and well - cared for.
In these fanfictions, their relationship can develop through shared battles. When they fight side by side against tough opponents, they understand each other better and their trust deepens.
Sasuke might show his protectiveness by always being near Naruto in dangerous situations. For example, if they are in a battle, she would quickly jump in front of Naruto to shield him from attacks.
She often uses her physical abilities. For example, she uses her shield to block attacks aimed at Percy.
Minato might show his protectiveness by always being near Naruto in spirit. For example, he could leave behind some kind of jutsu or power that activates when Naruto is in great danger, like a hidden seal that releases a powerful defense.
Luffy would be extremely angry and sad at the same time. He might roar out in pain and frustration.
In many such fanfics, Percy uses his intelligence. For example, he might study the laws and regulations of the wizarding world thoroughly to find loopholes that can protect Harry from unjust punishments or accusations.
Luffy shows his love for Nami in a very unique way. He gives her a great deal of freedom on the ship. He allows her to manage the money, which is a big sign of trust. Also, his constant protection of her is another way. For instance, during battles, he makes sure Nami is safe. He doesn't question her navigation skills and always follows her lead in that regard. His simple gestures like sharing his food with Nami also show that he cares about her in his own Luffy - like way.
They might use their humor. For example, if someone is making Hermione feel bad by teasing her about her studious nature, Fred and George will crack jokes at the teaser's expense, making Hermione laugh and feel better, which is a form of protection in a way.