Harry might be initially confused. He's used to their adversarial relationship, so this sudden change would be unexpected. He could be a bit resistant at first, not wanting to be coddled.
On the other hand, Harry could also find it endearing in a way. After all the hardships he has faced, having someone care for him like that, even if it's Draco, could bring out a different side of him. He might slowly start to accept Draco's behavior and even grow to rely on it to some extent.
Over time, Harry might use this to his advantage. He realizes that Voldemort's perception of him as a baby could be a weakness in Voldemort's strategy. So he starts to act more meek and innocent in front of Voldemort, while secretly planning his next moves. This way, he can catch Voldemort off - guard when the time is right.
Well, in many fanfictions, Draco might initially be shocked. He's used to being in an adversarial relationship with Harry, so hearing such a confession would be completely unexpected. His first reaction could be disbelief, like he might think Harry is playing some sort of cruel joke on him.
Harry's reaction can be complex. At first, he may show immediate resistance, arguing that he's been wrongly accused. When he realizes that arguing won't get him anywhere, he might become sullen and withdrawn. However, this sullenness is also a sign of his determination not to let them break his spirit. He'll keep thinking of ways to prove his innocence or to show that their punishment is unjust. In some fanfictions, Harry also uses these punishments as a motivation to become better at magic, so that he can one day stand up to Snape and Draco more effectively.
Harry might initially be very angry and hurt. He could cut off all communication with Draco and become withdrawn. In some fanfics, he would even start to avoid places where he might run into Draco.
Often, Harry reacts with anger. He's not one to take being cheated on lightly, whether it's in a relationship or in a competition. His Gryffindor pride kicks in, and he'll want to confront Draco immediately.
Draco might become withdrawn. He could isolate himself from his friends and spend more time alone in the Slytherin common room, brooding over what Harry has done to him.
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.
Harry might be confused at first. He doesn't understand why Draco would think he's a doll fan. So he might just shrug it off and not pay much attention, thinking Draco is just being his usual difficult self.
Draco might be initially skeptical. But as Harry goes into details, he could become more empathetic.
Harry might be initially shocked. He's used to seeing Draco as this tough, arrogant Slytherin. But then, he could feel a bit of pity. He might approach Draco tentatively and ask what's wrong. Harry has a good heart, and despite their past differences, he wouldn't just leave Draco crying. He may even offer some words of comfort or a handkerchief if he has one.