One common theme is redemption. Draco is often seen as a character who needs to be redeemed, and Harry's protection plays a part in that. For example, Harry's actions can make Draco realize there's more to life than following the dark path.
The theme of sacrifice is also present. Harry may have to sacrifice his own safety or reputation to protect Draco. This shows the depth of his care for Draco, and it adds a lot of drama and emotional depth to the fanfiction stories.
One common scenario is in a dangerous magical situation. For example, in a battle at Hogwarts, Draco might step in to protect Harry from a dark wizard's spell. Another could be in the face of social threats within the school. Maybe some students are trying to bully Harry, and Draco, having a change of heart, defends him. It could also be that Draco protects Harry from a plot within the Slytherin house that aims to harm Harry due to his fame as 'The Boy Who Lived'.
Love is a very common theme. Harry's love for Ginny makes him want to protect her at all costs. Another theme is heroism. Harry is often depicted as the hero who steps up to keep Ginny out of harm's way.
One common theme is loyalty. Blaise shows his loyalty to Harry in the face of danger or adversity. It could be protecting Harry from other students who might be bullying him or from more serious threats like dark wizards.
One common theme is redemption. Slytherins are often seen as the 'bad guys' in the original series, so protecting Harry gives them a chance at redemption. For example, they might be trying to make up for past wrongs or the actions of other Slytherins.
One common theme is redemption. Many fanfictions explore how Draco, who was often seen as a bully in the original series, can find redemption through his relationship with Harry. For example, he might realize the error of his ways and strive to be a better person with Harry's influence.
In many cases, the main antagonists can be other Slytherins who still hold grudges against Harry or are loyal to the pure - blood supremacist ideology. They might see Harry as a threat to their way of life. Also, some Death Eaters can be antagonists. They target Harry because of his role in Voldemort's downfall and would stop at nothing to get to him.
One common theme is redemption. Draco is often depicted as having a chance at redemption through his relationship with Harry. For example, in many stories, Draco realizes the error of his ways under Voldemort's influence and Harry helps him turn a new leaf.
One common theme is friendship. Many fanfictions explore how these three characters, who start off with a lot of animosity, especially Harry and Draco, can form a friendship. Another theme is rivalry turned into cooperation.
One common theme is redemption. Draco often has to atone for his past actions towards Harry, and his act of comforting is a part of that redemption arc. It shows his growth from a bully to someone who can be empathetic.
One common theme is redemption. For example, Draco often has a journey of redemption in these fanfictions. He may realize the error of his ways and try to make amends, especially in relation to Harry and Snape. Snape's complex loyalties also play into this theme as his actions are re - examined in the context of the fanfiction.