CrowFeri

CrowFeri is the slash ship between Crowley Eusford and Ferid Bathory from the Seraph of the End fandom.

Canon
In the anime, Crowley and Ferid seem close, appearing together many times, and Crowley appears when Ferid called for him. Together, they were also the ones that staged a rebellion against the vampire queen, Krul Tepes. Crowley has also been referred to be a part of Ferid's faction.

In the manga, they are also together many times. They were traveling together while Ferid was trying to find Shinoa squad to preventing them from escaping. Ferid has also commented that Crowley's blood had tasted good as a human.

However, their main backstory take place in the light novels. There, Crowley was still a Templar knight that has lost his faith after fighting in the crusades. There, he had seen a bloodsucking moster (who he later discovered was a vampire), and he believed that he had seen satan. He meets Ferid while investigating the deaths of some prostitutes that had died after being cut up and their blood drained out. Crowley thought that Ferid was a very beautiful man. While they talked Crowley thought that Ferid seemed very perverted, and even asks him if he were a sodomite, but he also notices how observant Ferid was in the situation, After, Ferid invites Crowley to his mansion, where they were many young servants wearing clothes that looked see-through at the right angle. Crowley asks Ferid if he were interested in these servants, but Ferid replies that he wasn't and that he just wanted to please Crowley. He also mentioned that he wants to see Crowley in these clothes. While investigating the deaths, Ferid had prevented Crowley's death by delaying their travel to a village where all the residents were killed, and he also helped Crowley come to the conclusion that it was the Templar order that had staged these deaths. Later, Ferid says that he gets bored when Crowley is not around.

However, Ferid also killed many of Crowley's comrades and forcefully turns Crowley into a vampire by feeding him Saito's blood. When they meet again a few decades later, Crowley tries to kill Ferid. He says that he came for revenge, and that he could only think of Ferid's face because getting revenge from him was his only reason for living. Ferid then reveals that he turned Crowley into a vampire because he wanted a friend, and says that vampires make companions to share their despair with each other. Ferid also reveals that he had been targeting Crowley for 150 years before he had turned him into a vampire.

Fanon
The ship is fairly popular among fans, especially how flirty Ferid treats Crowley. They also have the most screentime with each other as compared to their screen time with other characters. However, there are some people that dislike the ship due to how Ferid killed Crowley's friends and because of how Crowley seems to hate Ferid before he became a vampire and lost his emotions.

They are the 5th most written Seraph of the End ship on AO3 and the most written ship for each character.

Fandom
Ferid Bathory/Crowley Eusford on AO3

Trivia

 * According to the Fanbook 108, Crowley's favorite place is where Ferid is.
 * Even though he thinks that everything is tedious, he would still go if Ferid called him.