Zeus might initially be somewhat indifferent as he has had many affairs in the past. But he would also have to deal with the consequences of his actions. He would face the wrath of his family and the potential for a rebellion among the demigods. Annabeth's family, if they were alive, would be devastated. Her mother, Athena, would be deeply disappointed as she has always been associated with wisdom and this goes against all that. And the general public in the story's world would be scandalized. It would be the talk of the divine and demigod realms for a long time, and everyone would be watching to see how the situation unfolds.
The other gods would have mixed reactions. Some might be amused or see it as an opportunity to gain an advantage. For example, Hera, Zeus's wife, would be extremely angry and might seek revenge on Annabeth. The other demigods would be divided. Some might pity Annabeth, while others might see her as having overstepped or being too ambitious. The child, if it was born, would be a source of both hope and fear for different characters. It could be seen as a powerful ally or a dangerous threat depending on who you ask.
In such a fanfic, one possible consequence could be a major upheaval in the world of the story. The child would be of divine and demigod lineage, which might attract all kinds of unwanted attention from other gods and mythical beings. It could also lead to a power struggle as different factions might try to use the child for their own purposes.
Jaime could be torn between his loyalty to his family (if we consider the complex family dynamics in the original story) and his new - found responsibility towards Sansa and the unborn child. He might try to find a way to make things right in his own way. Sansa would start to think about how this affects her political standing and her relationships with other characters. She may seek out allies who can help her through this difficult time, all while dealing with the emotional turmoil of being pregnant in such strange circumstances.
Sakura would probably be very shocked and disappointed in Naruto. She has always had deep feelings for him. Kakashi might be more level - headed, trying to figure out how to handle the situation from a strategic and diplomatic point of view.
Gohan would likely be extremely shocked and angry. He is Pan's father and would have a hard time accepting this situation. Vegeta might be disappointed in Trunks, as it goes against Saiyan propriety. Bulma would probably be worried about the implications for the family and how to handle the situation. Goten might be confused and not know how to react, as it involves his nephew and niece in a very unexpected way.
Percy would become a fierce guardian. He'd use his skills in combat and his connection to water to create barriers and defenses around Annabeth. Annabeth would be using her wits to analyze their situation. She'd try to figure out if there are any hidden powers or advantages in Tartarus that could help them during the pregnancy. The other characters like Grover might try to use his nature - related abilities to find food and resources that are safe for Annabeth to consume. And they'd all be praying to the gods for some sort of miracle or assistance, while also being prepared to face whatever challenges come their way without relying too much on divine intervention.
Annabeth might be initially shocked and a bit flustered. She's a composed person, but this unexpected act from Percy would catch her off - guard. Percy, on the other hand, might be a bit proud of his 'mark' on Annabeth at first. Their friends like Grover could be really surprised and might tease them about it, while some of the more serious demigods might be a bit disapproving, thinking it's not appropriate behavior for heroes.
Some fans would be really excited. They might love the idea of seeing their favorite characters in a more mature and family - oriented situation. It could add a new dimension to the Natsu - Lucy relationship that they've always wanted to see.
Ron's friends from school could be divided. Some might ostracize him for getting involved with a known villain like Shego. Others, who are more open - minded, could see the situation as an opportunity for Ron to change Shego for the better. And Shego's villainous acquaintances might try to use the pregnancy to their advantage, either by blackmailing Ron or trying to turn Shego against him.
Well, Percy is a complex character. His reaction could depend on how much he knew about the pregnancy before Annabeth left. If it was a complete surprise, he might be in denial for a while. He could also start to blame himself, thinking he had somehow failed her. And then he might eventually turn that pain into a determination to be a better person, whether or not he ever sees Annabeth again.
Harry would probably be in a state of shock and disbelief at first. He'd be filled with a mix of fear, confusion and anger. Voldemort might be initially dismissive or see it as an opportunity to further his own dark plans. Hermione would be practical, trying to find solutions in books and magic. Ron would be more likely to be openly disgusted at first but might come around to support Harry as a friend.