Scipio (nicknamed Skippy) was Reyna's pegasus, nicknamed after the peanut butter brand, Skippy, because he was colored like peanut butter.
During Camp Jupiter's War Game, Reyna acts as referee for the game and flies around on Scipio so she can get a clear view of the Field of Mars. Later, Scipio aids Reyna in the battle between Polybotes' army and Camp Jupiter by attacking Polybotes from the air.
Reyna uses Scipio to fly across the Atlantic Ocean to reach the Argo II. Her mission was to carry Athena Parthenos to Camp Half-Blood as a sign of peace treaty between the Greeks and the Romans. During flight she was attacked by a gryphon.
After landing aboard the ship, Scipio had collapsed, overwhelmed by poisoned claw marks from a gryphon attack. Reyna had to put the horse out of his misery with her imperial gold knife.
It was found out that Reyna lent Scipio most of the strength she can give when flying across the Pacific. The kindness that she demonstrated to him when crossing the Atlantic is what earned her the title "Horse Friend", given to her by Pegasus.
As Hazel points out in The Son of Neptune, Scipio is the only pegasus at Camp Jupiter. Before Hazel tames Arion, she is jealous because only Reyna is allowed to ride Scipio, and the unicorns are only for medicinal purposes.
Scipio is named after the Roman General Scipio Africanus, who defeated Hannibal during the Punic Wars.
He is the only pegasus seen in The Son of Neptune, for Blackjack is only mentioned.
Scipio is Reyna's other pet, aside from Aurum and Argentum.
Scipio is one of the five named pegasi, the others being Blackjack, Guido, the original Pegasus, and Porkpie.
He is reforming, because of his Pegasus blood.
Pegasus, so far, has a different color than the standard black or white.