In fanfiction, it could be related to a love - hate relationship. Maybe Draco has a love interest who is angry with him. So, in a fit of rage, they use a spell to drag him behind them. Or it could be part of a magical duel where he loses and is then dragged behind the victor as a sign of defeat. Another idea is that he's being dragged behind in a quest or adventure where he's not fully on board, but others are making him participate by force.
One possibility could be that Draco is being forced into a situation against his will. Maybe he's being dragged behind in a magical chase where his enemies are after him, and his friends or foes are pulling him along as they flee or pursue. It could also be part of a prank gone wrong in the wizarding world, where he ends up being dragged behind someone's magical transportation device.
Well, perhaps in the fanfiction, Draco has been caught up in some dark magic plot. He might be dragged behind as a captive, being taken to a secret location. The ones dragging him could be dark wizards or witches who have plans for him, either to use him as a pawn in their evil schemes or to extract some sort of information from him. It could also be a situation where he's being punished by his own Slytherin peers for some misdeed, and they are literally dragging him behind them as a form of humiliation.
It might imply that the fanfiction is taking Draco out of his normal or expected context. So, instead of following the canon storyline, the fanfiction is 'dragging' him into new and uncharted territories, like making him interact with characters he would never meet in the original story or putting him in situations that force him to grow or change in ways not seen in the original series.
His character could develop through the experience of being dragged behind. He might become more defiant, vowing to never be in such a powerless position again. For example, he could start training harder in magic to protect himself.
Another example is that Draco could be dragged into a time - travel adventure in fanfiction. He might be unwillingly pulled into a situation where he has to travel back in time and interact with the founders of Hogwarts. This would be a huge departure from his normal life at Hogwarts and would force him to adapt to a very different environment.
Relationships also play a big role. The collar can be a catalyst for new relationships or a strain on existing ones. For example, it might change how Draco interacts with his friends, family, or enemies in Hogwarts. It can create interesting scenarios where characters have to re - think their feelings towards Draco because of this new element in his life.
One possible plot could be that Draco is caged due to some dark magic spell or political intrigue. While caged, he discovers he is pregnant, perhaps as a result of some experimental magic gone wrong. His friends, or even former enemies, then have to figure out how to break the spell on the cage and deal with his pregnancy.
Well, perhaps it could be about Draco's struggle to regain his reputation after the war. Maybe he's wrongly accused of being a 'whore' and has to fight against the false rumors. He might be trying to prove his true self to his friends and family.
One possible plot could be that Lucius is trying to punish Draco for some disobedience or failure. Starving him could be a form of extreme discipline in a very dark and cruel Malfoy family dynamic.
One possible plot could be that Draco is in a situation where he is being controlled by a leash for some magical or political reason. Maybe he's being paraded as a symbol of a new order in the wizarding world. His former Slytherin pride is put to the test as he has to endure this public display.
I'm not very familiar with this specific type of fanfiction. However, you can try searching on popular fanfiction websites like FanFiction.net or Archive of Our Own. There might be some works that match this description, but it could also be a relatively niche concept.
Well, perhaps the fanfiction explores how Draco has to face this unusual Boggart. He might initially be ashamed or try to hide it from others. But as the story progresses, through the help of his friends like Harry and Hermione (yes, an unlikely alliance in a fanfic), he starts to understand the root of his fear of Lucius and tries to change the family dynamic.