He is a Romanian with split personalities: a soft, kind, and overly-emotional "normal" side, and an aggressive, cocky, "battle-mode" side. The dominant personality is easily distinguished by his facial appearance. When 'normal', his long strand of white hair hangs down in his face. In addition, his appearance is kind and somewhat down-cast, and his voice is soft and low. When he enters his "battle-mode", the white strand of hair on stands up. Additionally, the whites of his eyes turn black and veins protrude from his face, making him look like a monster. He also talks loudly and aggressively when battling.
For his entire life, Krory lived in a secluded castle. Because of the way he attacked villagers, drinking their blood and then carrying them off, and because of his stereotypical vampire theme, he was believed to be a vampire by the surrounding villagers and shunned. The true reason for this behavior was his teeth, made of Innocence, that caused him to instinctively attack Akuma, though the villagers and Krory (before meeting Allen and Lavi) did not know this. Later, he fell in love with a woman named Eliade, unaware of the fact that she was actually an Akuma. After Allen and Lavi come across the village and their "vampire problem" during their search for Cross, they realize that Krory has innocence, and recruit him as an Exorcist. It was around this time Lavi dubbed him "Kuro-chan" or "Krorykins", despite the fact he dislikes being called so. Krory is still getting used to the "outside world."
He first appeared in Chapter 31 when Allen and Lavi are recruited into "vampire hunting" for a village. After Krory takes another victim, Lavi and Allen follow him into the castle. It turns out that Krory has been living alone in his grandfather's castle with Eliade, the woman he loved, and does not wish to be a vampire. After Eliade discovers the two Exorcists, she tells Krory about them. Meanwhile, the Lavi and Allen dig up the bodies of the villagers he attacked, discovering they are the bodies of Akuma. They speculate Krory may be instinctively attacking Akuma because of Innocence. However, Krory appears to confront Lavi and Allen. Lavi explains Krory's situation with the Innocence. Meanwhile, Allen discovers Eliade is a level 2 Akuma. Later, Krory discovers this too and regretfully kills her. After an attempted suicide, he decides to become an Exorcist as an excuse for killing Eliade.
After being thrown out of the village, he accompanies Allen and Lavi on their search for General Cross. He comes across a bunch of vagabonds, one of whom is the Noah Tyki Mikk and is suckered into playing poker with them. After losing all his possessions, he is saved by Allen, who turns the tables through cheating.
The three meet up with Bookman and Lenalee and travel to China and take a ship to Edo. Krory is one of the Exorcists who try to protect the ship from the Akuma and level 3 attack out at sea. He is also one of the Exorcists who chases after Lenalee and into the Ark when she's kidnapped by Lero. Inside the study room, he's the only one who can pinpoint the Noah Twins Jasdevi's location in spite of the fact he cannot see them and directs Allen in capturing them. He later tells the rest of the group to go on ahead, he'll take care of them. In the battle, Krory goes up against the merged Jasdevi and seems to be defeated, having been locked in an Iron Maiden. But he uses a new technique, Bloody Krory, to defeat the Noah. Although he defeated them and managed his way out of the Iron Maiden, he passes out as the room collapses. Later, he is revived with the other "lost" Exorcists when Allen restores the Ark. However, he had not regained consciousness immediately after and was seen being attended to at the Black Order Headquarters by the Head Matron during Lulu Bell's assault and the level 4 attack on the building. He recently woke up but was chained to the bed he was in and a young lady was inside the room. She has possibly poisoned him as seen in Chapter 159 where a bottle with skull and cross-bones dropped onto the floor. After Allen fainted, he had a "dream" that Krory was in great agony. Although shortly after, Krory is supposedly knocking on the door of the storage room Allen, Lavi, Kanda, and Johnny are hiding in. Subsequently after he was let in, he started to launch an assault on the room refugees and was eventually identified as the origin of the infection after he spat out the lid of the bottle in which the virus was stored.
Krory received his Innocence from a plant Cross Marian gave to him. The plant bit Krory afterwards. After agonizing pain, his teeth fell out and were replaced by his parasitic form of Innocence. The strength of his Innocence lies in his blood, allowing him to manipulate the blood in his body and, to an extent, others' bodies. When invoked, it grants him feral-type abilities and enhanced overall strength, such as increased strength, speed, and agility. And because the Innocence allows him to break down Akuma poison, Krory can drink the Akuma's blood, which he comments tastes like tomato juice. The blood allows him to quickly regenerate and temporarily increase his strength. But he is not immune to the poison, as seen in his fight with Jasdevi on the Ark, when his body is too weak to break down the poison. Krory is also able to remove the poison from another person by drinking their blood. On the other hand, he can also inject his blood, laced with Innocence, into the Akuma by biting them. Although this kills them in seconds, it also weakens him. Krory has dubbed this ability "Crimson" ( 紅 ,), because the Akuma disintegrates into tiny red particles, which Miranda likened to "crimson snow". He is also capable of wrapping blood around his hands to fortify the flesh beneath. In addition, Krory can drain the blood from his body and wield his maximum strength remotely as an almost invulnerable, winged blood mannequin called "Bloody Krory" ( 血のクロウリー , "Bloody Krory"), which is also seen during the height of his battle with Jasdevi. The limits and full power of this ability is yet to be revealed. But, by using "Bloody Krory," Krory was able to defeat Jasdevi, a powerful Noah, with no apparent problems. However, after using this technique he becomes so exhausted he cannot stand or move. But this may have occurred due to his imprisonment in an Iron Maiden.