He could also be deeply saddened and go into a state of depression. His familiar was likely a great source of comfort and companionship, and its loss would leave a huge void in his life. He may withdraw from others and become more solitary.
Draco might be extremely angry. He could immediately seek revenge on Nott, not caring about the consequences. His anger would be fueled by the loss of his familiar, which was probably very dear to him.
One possible motive could be envy. Maybe Nott is jealous of Draco's relationship with his familiar and wants to hurt Draco by taking away something he cares about.
Well, in fanfics, when Harry is Draco's familiar, it often means there's a magical bond between them. This bond can be used for various plot devices. For instance, they can communicate telepathically, which is a common trope. Harry might be able to sense Draco's emotions or danger.
Well, in some fanfictions with this concept, it might involve Harry being magically bound to Draco in a familiar - like way. This could lead to all sorts of interesting situations, like they have to work together more closely than they ever thought. Maybe Harry has to follow Draco's commands in certain magical tasks, which creates a power dynamic that's different from their usual rivalry.
Harry would likely develop a different sense of loyalty. Since he's Draco's familiar, he might start to understand Draco's motives and actions better. He could become more patient and less quick to judge. Draco would probably develop a sense of protectiveness towards Harry that he didn't have before. He may also become more empathetic as he realizes the impact his actions have on Harry.
Draco might be extremely frightened. He could become more cautious around Harry, always looking over his shoulder. For example, he might avoid being alone in the same room with Harry, fearing a repeat of the incident.
The wizarding world would be in chaos. Harry is seen as a hero and the 'Chosen One'. His death would leave a huge void. The Order of the Phoenix would be devastated and might seek revenge on Draco and those associated with him. Hogwarts would also be in turmoil, with students and teachers alike shocked and saddened. There would be a great deal of fear as well, as Voldemort's forces might see this as an opportunity to gain more power.
There's also 'Familiar Ties'. This fanfic delves deep into the magical implications of Harry being Draco's familiar. It's interesting as it not only focuses on their relationship but also on how the wizarding world reacts to such an unorthodox situation. For example, it shows how other students and teachers perceive this new relationship between the two rivals.
Well, Draco could be very conflicted. On one hand, he has his own pride and his Slytherin upbringing which might tell him to stay away. But if he has developed deeper feelings for Hermione in the fanfic, he might put aside their past differences. He could start by using his family's resources to find a cure or at least better treatments for her cancer. He may also become more protective of her, keeping her away from those who might be unkind about her illness.
The wizarding world would be in shock. Harry is seen as a hero, and for him to kill Draco, even if Draco was from a 'less popular' side, would be a huge scandal. His friends like Hermione and Ron would be deeply conflicted. They would be torn between their loyalty to Harry and their disbelief at his actions.
He could also react with suspicion. Draco might think that Harry has some ulterior motive, especially if the confession is of a more positive nature like friendship or love. He would question Harry's sincerity and might even test him in some way.