Grover would probably be really excited. He might bring all kinds of nature - related gifts for the baby, like a special plant that has protective powers. He would also be very protective of the baby, using his nature senses to detect any danger.
Piper would be super helpful. She could use her charm - speak to soothe the baby when it's crying. And she would be there for Annabeth, giving her advice on motherhood based on her own experiences with her father and how she dealt with family relationships.
Jason and Piper would be very supportive. They'd offer their help, like babysitting or providing resources. Piper might use her charm - speak ability to soothe the baby when it's fussy, and Jason could use his leadership skills to help Percy and Annabeth make important decisions about the baby's future.
Their pirate friends would probably be both excited and a bit clueless. Jack Sparrow might try to give the baby some 'unique' gifts like a small piece of treasure or a strange trinket. Gibbs would offer practical advice on how to keep the baby safe on a ship if they ever take it to sea.
The relationship could start with Percy and Annabeth being overprotective parents. Percy might be constantly worried about the baby's safety near water, while Annabeth would focus on teaching the baby knowledge and wisdom. As the baby grows, they could start to have little adventures together. For example, the baby could go on a mini - quest with them around Camp Half - Blood, which would strengthen their bond.
Percy would probably be very protective. He'd be constantly worried about her safety and would do everything he could to keep her out of harm's way.
Their friends would probably be very surprised at first. Annabeth, for instance, might be a bit skeptical at first but would soon come around to offer help and support. Grover would be excited and might offer to be the baby's protector, using his nature - related skills.
Chad would be a very protective and gentle presence. He would be like an uncle to the baby, always ready to pick the baby up and play with it. His calm and strong nature would make the baby feel safe.
Ban would probably be excited and start thinking about all the fun things he could teach the baby, like how to steal food without getting caught in a humorous way. King might be a bit more reserved at first but then offer to make the most beautiful crib with his powers. Diane would be super excited and offer to babysit all the time, cooing over how cute the baby will be.
The Salvatore brothers might be a bit protective at first. Damon would probably be skeptical about Kol being in the picture, but over time he'd warm up to the idea for Elena's sake. Stefan would be more accepting right away and offer his support. Bonnie would be excited and use her magic to make sure the baby is safe. Caroline would be all over helping with baby clothes and advice. As for the Mikaelson family, Klaus might see the baby as a way to strengthen his family's hold in the supernatural world, but also be protective in his own way.
Grover would be super excited. He'd probably start bleating happily and immediately start thinking about all the great food he could eat at the wedding. Jason would be very supportive and offer his help in any way he could, like with security for the big day. Piper would be thrilled and would probably start planning Annabeth's bachelorette party right away. Leo might crack some jokes about Percy finally tying the knot but deep down he'd be really happy for them.