Prince Blueblood

Prince Blueblood is a royal male unicorn pony who resides in Canterlot. He is the distant nephew of Princess Celestia and Princess Luna and the cousin of Princess Cadance. He starts out as the object of Rarity's affections, but once they meet, he turns out to not be what she was expecting.

Development and design
Before The Best Night Ever aired, Lauren Faust stated that Celestia's nephew had no name in the show and that he's the "great great great great great great great great great great great (and probably even more greats) nephew on Celestia's and Luna's mother's side, about 52 times removed, roughly speaking." He was originally a Duke, but was changed to a Prince because "someone in the approval process thought kids wouldn't know what a Duke is", though the title of Duke would eventually be used for other ponies much later. "Blueblood" is an English idiom for "nobility", or being of noble birth or descent. It has been recorded since 1834 and comes from the Spanish words sangre azul, describing Spanish royal families said to be descendants of the Visigoths.

Prince Blueblood shares his coat and mane colors and tail with "Persnickety", shares his color scheme and compass rose cutie mark with Léon, shares his coat color and crowns cutie mark with Fancy Pants, and shares his compass rose cutie mark with "South Pole", sometimes Blue Moon, and in some material Friends Forever 13 Unnamed Stallion - Doctor.

Depiction in the series
Prince Blueblood first appears in Rarity's fantasy in The Ticket Master, where she envisions Princess Celestia introducing her to him at the Grand Galloping Gala and the two of them swiftly falling in love and getting married. In The Best Night Ever, Rarity meets Prince Blueblood in person at the Grand Galloping Gala and he appears physically the same. Rarity expects him to court her as he did in her dream, but instead, he treats her with very little respect at all as during the night:
 * Rarity expects Prince Blueblood to give her a rose that he picked, but he takes it for himself.
 * He brings a cushion only for himself to sit in the castle's yard, leaving Rarity without a comfortable seat.
 * He expects Rarity to open the door for him.
 * He makes Rarity use her shawl to cover a puddle so he doesn't get dirty.
 * He expects her to pay for his dinner.
 * He inconsiderately dispraises Applejack's food in presence of her.
 * When Applejack's cake is catapulted across the room at him, he pushes Rarity in front of him to use as a shield so that he won't get messy.

Thus, it appears that Prince Blueblood is thoroughly accustomed to being treated like royalty and that he possesses no sense of chivalry whatsoever.

Throughout the entire Grand Galloping Gala, Rarity tries to make pleasant company with Blueblood, but his self-centered nature drives her to the point of extreme irritation. After he uses her to shield himself from an incoming cake, Rarity finally snaps and tells him off as the most "uncharming prince she's ever met", and shakes the cake all over him in retaliation. After the Gala descends into chaos, Rarity and her friends leave the scene, but she loses her glass slipper when running down a set of stairs. Pinkie Pie suggests that now her prince is sure to find her; panic-stricken at the thought, Rarity smashes the slipper and runs off.

In Sweet and Elite, Prince Blueblood appears during the song Becoming Popular (The Pony Everypony Should Know).

In Magical Mystery Cure, Prince Blueblood appears in one of Rarity's flashbacks.

In Equestria Games, Prince Blueblood appears as a spectator at the titular event sitting in between the delegates from Saddle Arabia and the Duke and Duchess of Maretonia. Here, his cutie mark is the same as that of Fancy Pants.

Merchandise
Blueblood is part of the trading card set: his card says he's Celestia's nephew, and that his family link to Luna and Celestia is "far removed". "You could call Prince Blueblood the most eligible unicorn bachelor in Canterlot, but you'll stop as soon as you meet this royal pain."

IDW comics
In, Prince Blueblood "gets involved in a sensitive diplomatic mission. Will Shining Armor be able to make use of the Prince’s unique talents?"

Magazines
Blueblood appears in a story from the French My Little Pony magazine. In this story, he is referred to as Vladímir, although it is inconsistent with his original name which has been also retained in the show's French dub.

My Little Pony mobile game description
At one time the object of Rarity's affections, Prince Blueblood is a royal colt whose favorite pony is himself.

The Elements of Harmony guidebook
PRINCE BLUEBLOOD may be of a noble background, but he's also quite vain, which is no doubt why Rarity once had a crush on him.

Appearances
Prince Blueblood appears in The Ticket Master, The Best Night Ever, Sweet and Elite, Magical Mystery Cure, and Equestria Games.

Quotes
"My royal lips have touched common carnival fare!"

- The Best Night Ever

"Ewww...! Uh, stay back! I just had myself groomed!"

- The Best Night Ever