In this fanfiction, Percy might sacrifice himself in a grand battle. He could be facing a powerful enemy that was about to strike Zoe. Percy, being the heroic type, jumps in front of Zoe at the last moment. His last thoughts could be of his friends and all the adventures he had. Zoe, in turn, is left with a deep sense of guilt and sorrow, vowing to carry on Percy's legacy. She might become even more determined to fight for the cause they both believed in, all while mourning the loss of her dear friend.
Zoe would likely be filled with guilt. She might constantly wonder why Percy had to sacrifice himself for her. There would also be a deep sense of grief, as she lost someone who clearly cared a great deal for her. She could become withdrawn, at least initially, as she tries to process what happened.
In this kind of fanfiction, it's often a very tragic and heroic concept. Percy sacrificing himself to save the seven would be a huge shock to the other characters. It might lead to a lot of grief and also a new sense of purpose for the remaining seven. They would have to carry on with their mission while also dealing with the loss of Percy, which could add a lot of depth to their character development.
The theme of legacy is also quite common. Percy's death leaves behind a legacy that the other characters have to uphold. They have to carry on his mission of protecting Olympus and also keep his memory alive. There's also often a theme of grief and how the characters deal with the loss of someone so important.
Zoe could become more withdrawn initially. Losing Percy, who was perhaps a close friend or love interest, would be a huge blow. But then, she might slowly turn her grief into strength. For example, she could become more determined in her fights, using Percy's memory as a source of inspiration.
Percy could be a brave and adventurous character, perhaps with some special abilities like being able to control water or having enhanced strength. Zoe might be a smart and resourceful female character, maybe with skills in tracking or archery. They could be from a fictional world full of magic and mythical creatures.
Maybe in the fanfic, Percy's death could be a sacrifice to save Zoe. This would then lead Zoe to live her life in a way that honors Percy's sacrifice. She could become a protector of the things Percy held dear, like a certain place or group of people. And as she does this, she has flashbacks of their time together, which are bittersweet memories that keep her going.
The main emotional impact would be grief. His friends in the seven would be deeply saddened. There would also be guilt for some who might think they could have done more to save him.
The characters would be devastated. Grover, Percy's best friend, would be heartbroken. He might lose his ability to find Pan because of the emotional turmoil. His search for Pan was always connected to his friendship with Percy, and without Percy, he could be lost.
Their interaction could be very emotional. Percy might be in shock at first to see Zoe again. He could be filled with guilt for not being able to save her when she was alive.