•  He actually has a very angular face - High cheekbones, narrow face, straight nose. He gets his bone structure from his mother, but where Sally had a softness to all of her features, he gets Poseidon’s natural brooding and regal sharpness. It’s another factor that makes his demeanor a bit intimidating and what makes people peg him as a trouble maker. and so so attractive
• When he was younger, he used to be left handed. But during the sporadic period when he was rapidly getting kicked out of school and learning how to write, he was placed through many schools that had the old philosophy that being left handed was wrong and forced him to write with his right hand. In the end, it ends up helping him because he learned how to use both hands equally well, becoming ambidextrous, thus also helping his sword fighting.
• When Sally married Gabe, Percy never told Sally of the abuse he was getting because he thought that if Gabe took out all of his frustrations on him, then there would be nothing left for his mother to receive and was afraid of what Gabe would do.
• After the Sea of Monsters but before the Battle of the Labyrinth Percy had a mouthful of braces. Annabeth took as many pictures as she could at the time and taped them on the wall of the big house. He tore down all he could find but legend has it, you can still find one or two miraculously appearing up there.
• His middle name is Dylann, pronounced Die-lin, which means ‘son of the sea.’ Subtlety is not Sally’s specialty and she cannot seem to give him names that are easily pronounced. Teacher’s sigh on the first day of school when they get to his name on their clipboard.
• Percy is the best get away driver. Paul took him out on his first driving lesson and it was something that came natural to him. And when he was homeless for that period in Son of Neptune and relied on stealing cars he got really good at getting away quickly and efficiently. Especially when he stole that police cruiser.
• Percy has scars on the insides of his elbows and forearms that almost look like a bad case of chicken pox scars. They’re actually cigarette burns from Gabe. Annabeth, Sally, Grover, are the only ones who know where they’re from.
• Percy’s clothing is badly torn up. Some is the result of monster fighting, and some is from the constant wear and tear because he refuses to get rid of old clothing, but a lot of it is from skateboarding accidents. He’s actually pretty decent at skateboarding but he’s also pretty decent at falling off of it too.
• Percy, Piper, and Rachel go skateboarding together sometimes.
• Before Tartarus, Percy’s eyes were a gentle, warm green, like the middle of a lazy ocean you could get lost in. But after Tartarus they’re fiercer, darker, like a wave in a storm about to drag you to the bottom of the sea.
• Percy’s favorite type of music is rock. He wanted to learn electric guitar but there was never money he was younger, now he’s too busy with monsters to have the time.
• Percy is a naturally good surfer, it comes freakishly natural just like anything else that has to do with the ocean. Piper and he go surfing together.
• When he’s fifteen he is around 5′11″ but he gets in a few more growth spurts before everything is said and done and ends up being just above 6′2″ and parallel to Jason. He loves playfully holding things out of Annabeth’s reach. She punches him when he does that of course.
• He has a lean build with prominent definition. He has very little body fat and most of his weight comes from his muscles. He has the perfect swimmer body, lithe and agile.  cinnamony roll goodness
• His hair is black like a raven’s wings and is always windswept and unruly as if he’s always running a hand through it  or like bed hair if you know what I mean
• He, unlike the other two greek kids of the big three, doesn’t have any freckles or moles of any kind. His mother has very clear skin and het gets it from her just the same, except with the tanner tone of Poseidon.
• He’s on Goode High’s swim team. He’s much faster than everyone even without his powers and he can’t tell if it’s just a son of Poseidon thing or if he’s actually good. Paul and Sally don’t mind because he knows that’s the only way Percy will get a scholarship with his grades, reputation, and attendance records.
• Percy is known as the weird kid in school. He has weird scars, disappears for months at a time, and has an off putting demeanor. He doesn’t talk to many people and only does when they talk to him first.
• His nervous ticks include running his hands through or tugging on his hair, and tapping or playing with Anaklumos in pen form.
• He walks quietly on his feet, this comes from many different things - Being silent so Gabe couldn’t hear him, trying to sneak past monsters, his training from Lupa, and the period of time he spent running, hiding, and stealing in Son of Neptune.
• He absolutely sucks at growing facial hair. It grows in in uneven patches and it disappoints him to no end. The guys make fun of him to no end during no shave November.
• He knows that people underestimate him, he knows that people think of him as a goofball, and he knows that people dismiss him as stupid. Now he uses that to his defense. After torturing the goddess of Misery he can feel that darkness growing in him and his powers growing more, so he spends the entirety of Boo trying to convince everyone he’s fine. He jokes, he smiles, he says stupid things. And for the most part it works. Jason, Leo, and Piper believe it easily, although Hazel and Frank are harder to convince. But he hates the knowing look in Annabeth’s eyes that barely hide that smallest look of fear.
• After Tartraus he figures out all the things he can do. That he control the blood pumping through someone’s veins. That he can stop someone’s heart stop with the clench of his fingers. That he can make someone die in an explosion of red. The idea terrifies him as much as it exhilarates him.
• He tries to keep his rapidly growing powers a secret which fails of course, because whenever he has a particularly bad nightmare the ground shakes. That now when he holds Annabeth’s hand he can feel the blood pulsing thickly beneath her skin, gravitating towards him as if he’s a magnet.
• He trains with Chiron to help find control for several months. 
• He finds unexpected support from Nico di Angelo, who had gone through a similar thing after Tartarus.
• He’s angrier often and snaps more easily. He purchases a punching bag and it helps him work through his aggression.
• Percy and Annabeth go to Montauk for two weeks after the war is over, and he breaks down. Annabeth helps him through everything, saying how he can’t keep everything inside all the time.
• Percy learns to control the darkness in him, and learns that while it may never go away, he will not be controlled by it.

“She’s mad but she’s magic. There is no lie in her fire.”