Percy
Percy had ran all the way to the bathroom when he saw the mess you had made while eating. Now, he wasn't a neat freak but he knew that the milk formula he gave you would soon start sticking to both you and him. And, like any other sane person, he didn't want baby formula all over him. Once he had gotten to the bathroom, he started undressing both you and himself. (Get your mind out of the gutter you pervs. Its normal for parents to bathe with their children when they're infants) Luckily, (and good news for you) not only did he buy all the required things needed to bathe a baby, he looked up how to do it while he looked up how to feed you! Yay for the internet! Anyways, as he set the water at the right temp, both of you climbed in and Percy tried bathing you. Keyword 'tried'. You refused to cooperate and was fully intent on just looking and playing with the bubbles. It took a good hour and 20 minutes, and about 10 gallons of water, before both you and Percy were clean. You had already fallen asleep about 20 minutes ago and, to be honest with you, Percy was beyond relieved. Percy quickly got himself dressed before putting a diaper and one of his old shirts on you. He walked as gently as he could to his parents' room with you in his arms (he was going to convert his old room into a nursery for you) and lay down on the bed with you on his chest. He quickly made a mental note to IM Leo tomorrow and ask him to make furniture for you before drifting off to sleep.
Jason
Surprisingly, you were a very cooperative baby and let him bathe you in record time. Jason was quite pleased with you and very quickly got you dressed and rocked to sleep in your nursery before cleaning both himself off and the mess you made. (Sorry I didn't have many ideas for this one)
Leo
Ok. Let's get something out of the way before we continue here. You are TERRIFIED of water (If your not, you now are. Your welcome) and Leo had no clue about this.... until you were kicking and screaming bloody murder. Leo had to hold a screaming you down in the water while trying to clean you, and both of you weren't pleased. Leo hated holding you down and you hated being in the water. Good news for Leo, you wore your self out and gave in within 20 minutes. That gave Leo enough time to properly bathe and dressing the both of you. You in a makeshift diaper and one of his old shirts and him in only boxers. (I feel so awkward typing that) He carefully carried you to his bed and made a small makeshift space for you to sleep in so you won't roll off the bed and hurt yourself. He put you in there and lay himself down facing you. As he went to sleep, he put his hand on your stomach and smiled.
Nico
With your nagging ghost mom telling him how to do everything, he didn't really have any trouble with you. He was able to bathe the both of you with no issues and he was able to dress the both of you in peace. After Nico started bathing the both of you, your mother was finally satisfied and passed on. Nico was beyond thankful for that and held you close to him as you both went to sleep.
Edit 6/14/18: Just doing some maintenance