In fanfiction, the pain could also be caused by Draco's internal conflict. He may not fully want to be associated with Voldemort and the Death Eaters, and this inner turmoil could manifest as physical pain from the Dark Mark. His conscience is at war with the actions he is forced to take because of the mark.
The presence of other powerful magic around him could also cause pain to his Dark Mark. For example, if he is near a strong source of light magic, like a powerful wizard who is a strong opponent of Voldemort. The clash between the light magic and the dark magic of the Dark Mark could result in pain for Draco.
One possible cause could be the dark magic that is constantly active within the mark. The Dark Mark is a symbol of Voldemort's power and control, and the dark magic it contains might be constantly causing pain as a reminder of Draco's loyalty to Voldemort.
In some fanfictions, Draco might use magic potions to ease the pain. For example, he could seek out a special healing potion from a hidden apothecary. These potions are often created with rare ingredients and have strong healing properties.
One possible cause could be his sense of failure. Naruto always wants to protect his friends and village, so if he fails in a mission or is unable to save someone, it can cause him great pain.
In fanfiction, Draco's connection to the Dark Mark often serves as a source of internal conflict. Writers explore how he grapples with the mark's implications and his family's ties to the Dark side. It can be a powerful device to show his character development.
In some fanfictions, Draco's Dark Mark is shown as a constant source of pain, both physical and emotional. It's a reminder of his family's allegiance and his own mistakes.
One possible cause could be the aftermath of the war. He was on the losing side, and he might feel guilty for the things he did during the war, like helping the Death Eaters. He might be haunted by the memories of the violence and destruction he witnessed or was a part of.
In terms of his relationships outside of Slytherin, like with Harry Potter and his friends, his refusal of the Dark Mark could be a step towards possible friendship or at least a mutual understanding. They might see him in a new light, as someone who is not as bad as they initially thought. However, they may also be skeptical at first, doubting the authenticity of his refusal.
One motivation could be love. Maybe he has fallen in love with a non - Death Eater, like a Gryffindor girl, and doesn't want to be part of the dark side. Another could be fear of the consequences. He might have seen what the Dark Mark has done to others, like how it controls them, and he doesn't want that for himself.
One reason could be his underlying sense of good. Despite his family's alignment with the Dark side, Draco might have a moral compass that rebels against the evil associated with the Dark Mark. He may have seen the destruction and pain it causes and doesn't want to be part of it.
One cause could be the pressure of living up to the pure - blood family standards. He might think that a certain body type or appearance is expected of him. Another possibility is the stress from his role in the wizarding world's conflicts. For example, the tasks he was given during the dark times at Hogwarts could have been so overwhelming that it affected his eating habits.
One possible scenario could be that Draco realizes the true evil of Voldemort and the Dark Mark represents everything he doesn't want to be. He might see Hermione's strength in the face of the Dark side and be inspired by her. Maybe he secretly helps the Order of the Phoenix instead of joining the Death Eaters, all while falling in love with Hermione.