Servamps are said to be the first original vampire siblings that exists in the world. However, as the story progresses, it's revealed that the Servamps didn't just come into existence, but were rather humans changed into immortal vampires by a certain human hundreds of years ago. There are supposedly only seven Servamps in existence who each represent the seven deadly sins, but it's later revealed that there's the eighth Servamp who even the other Servamps didn't know exist. All of the Servamps have street names and given names, and some also have nicknames. These names are most likely given by the Creator of Servamp. When they are not serving someone, they are usually referred by their street name or the sin they represent. All Servamps are able to change into animals. They usually change into their animal forms when exposed to sunlight, though they can freely switch between their human forms and animal forms at will.
Servamp is the combination of the terms Servant and Vampire, which means they are vampires meant to serve a master (human). There are four conditions for a human to make contract with a Servamp. The conditions are:
- Gives the vampire a name.
- Gives the vampire a present.
- Calls the vampire with their given name when the vampire is in human form.
- Makes the vampire drink the blood of the human who has done the three conditions above.
Once all four conditions above are fulfilled, the Servamp and their human master called Eve, will be connected by a chain that binds the Servamp's neck and the Eve's wrist or ankle. This chain will appear every time the Servamp drinks the Eve's blood. Once the contract is made, the Servamp can only drink the blood of their Eve and their powers depends on how strong the will of the Eve flowing in the blood. If the Eve's will is strong, then the Servamp will get a significant power up. If the Eve's will is weak, then the Servamp will only get weaker. Servamp's dispositions completely change depending on who they contract with, including their reasons for fighting. Servamp is obliged to listen to the Eve's order, though there are times they can refuse to follow the order even if the Eve forced them.
There are distance limit for Servamp and Eve when they are separated. If they got separated too long, the consequences are as follow:
- After 6 hours passed since they got separated, the Eve's body will experience abnormalities such as nausea, dry eyes, headaches, etc.
- After 18 hours passed since they got separated, both Eve and Servamp will change into the Servamp's respective animal form.
- After 24 hours passed since they got separated, the Eve will die.
If the Eve begins to feel unsure and even fear their own Servamp's power, their feelings will overflow within their Servamp's mind and the Servamp will lose control of their own power, causing them to gobble up their own Eve whole. So far, the only way to stop the process once the Servamp lost control is from outside interference such as attacking the Servamp several times until the Servamp calms down or forcefully freeing the Eve from the Servamp's body.
Contract Item is an item that Eve gave to vampire as a present along with their name. This item constitutes the link between the Servamp and Eve and is the source of the Servamp's power. As long as the trust between Servamp and Eve is strong, the contract item won't be easily destroyed no matter what kind of item it is, though Tsubaki has a power to break the item without severing the trust between the Servamp and Eve. If the contract item is destroyed, a huge amount of Jins will comes out from the Servamp's body and the Servamp will lose their power. Along with losing power, there are changes in the Servamp's behaviour as well from simple to drastic changes. As times passed, the Servamp's body will grow weaker and smaller, which may eventually led to their death.
Temporary contract is made when the human completed the first three conditions but has yet completed the final condition. As the name indicates, this contract is only temporary and will be cancelled as long as the vampire doesn't drink the blood of the human who makes the contract within 24 hours. Until 24 hours have passed, the Servamp and Eve cannot be separated a certain distance, when they are trying to separate, a chain that connects the Servamp's neck with the Eve's wrist or ankle will appear to prevent them from getting separated. The colour of the chain depends on the colour theme of the Servamp.
He is the Servamp that represents Sloth and the oldest of the vampire siblings. He once had a close relationship with the creator of Servamp, but later decided to kill him after deeming him too dangerous, an action that he later regretted. True to the sin he embodies, Sleepy Ash is lazy and neet, having little to no motivation in doing anything unless he is ordered to and mostly spending his time lazing around. His laziness hides his true power as the strongest Servamp and his true feelings for the people around him that usually manifested as a Black Cat taunting his contradicting actions and words in his mind. Unlike his siblings, he has two animal forms, a small black cat and a giant black lion. He uses claws and the tips of his jacket that he can hardened or produces spikes to fight. He is currently contracted with a high-school sophomore, Mahiru Shirota who renamed him Kuro with a yellow cat bell as his contact item.
He is the Servamp that represents Pride with nickname "One Forgotten by the Good Ol' Days". Despite his child-like appearance, Old Child is the second oldest of the vampire siblings. True to the sin he embodies, Old Child has a big pride as a vampire, thinking highly of both himself and his race and dislike anyone who simply thinks that Servamps are merely a tool that being used or controlled by humans, stating the vampires are the ones who used humans. He often boasts about himself and thinks he is the most important person and demands to be treated first before everyone else. However, this trait is often overlooked by his childishness. His animal form is a bat. He is currently contracted with the son of a hot spring lodge owner, Tetsu Sendagaya who renamed him Hugh the Algernon III or simply Hugh.
He is the Servamp that represents Envy. His nickname is "Punisher of the Doubtful". Together with All of Love, he has served the Alicein family for generation after being invited by him. He is a quiet vampire who rarely talks but has quite a short temper when things doesn't go his way and can be easily tricked. 7 years before the main story, his Eve who was the wife of the current Alicein householder, got corrupted by his power and the sin he embodies, leading her son to kill her before she could kill his younger brother out of jealousy. After the incident, Doubt Doubt was banished from the Alicein household together with his former Eve's son, accompanying him since then. His animal form is a snake. He is currently contracted with the son of his previous Eve, Mikuni Alicein who renamed him Jeje.
The only female Servamp, she is the Servamp that represents Wrath. She always looks frowning or grouch, giving other people impression that she is angry, which fits the sin she embodies. However, despite the sin she embodies, she is said to never gets angry so easily without a clear reason and always remain calm. She was married to her Eve who was an apple farmer, until he passed away a week before her confinement in C3 due to old age. She is currently under temporary contract with a C3 inventor, Izuna Nobel who renamed her Freyja. Her animal form is a wolf.
He is the Servamp that represents Greed with nickname "One and Only". After the death of his previous Eve, Ophelia whom he fell in love with, and his creator at the hand of his oldest brother, Lawless goes against the sin he embodies, never wishing nor wanting for anything as he devalues his own and other people's lives. To cope with his loss, he developed a habit to choose only celebrities as his Eves and then killed them when he got bored of them. He eventually regained his true feeling and desire after overcoming his sadness and come into terms with his loss. He uses a rapier that he made from his scarf to fight. His animal form is a hedgehog. He is currently contracted with a famous young pianist, Licht Jekylland Todoroki who renamed him Hyde with a hand carved necklace made by Licht as his contract item until it was destroyed by Tsubaki.
He is the Servamp that represents Gluttony. True to the sin he embodies, he has a big appetite, capable of finishing the entire menu of a restaurant. A self-proclaimed rival to his oldest brother, he has a very short temper and noisy, mostly talking in loud voice comparable to shouting. His animal form is a pig.
He is the Servamp that represents Lust. While he supposedly represents lust, he never shows any slightest bit of interest in any sexual activity. His representation of lust seems to be shown in his habit of trying to strip. He takes children who are abandoned or victims of abuse, turning those whom he couldn't saved into his subclasses. He showers all children he saved with love that looks like his way to repent for the sin he embodies. He has been serving Alicein family for generations, vowing to protect the family in exchange they accept him and his subclasses to stay with them. He uses a scythe and illusion in battle. His animal form is a butterfly. He is currently contracted with the second son of Alicein household, Misono Alicein who renamed him Snow Lily with the pocket watch used to belong to his previous Eve as his contract item until it was destroyed by Tsubaki's subclass, Otogiri.
He is the eight Servamp that represents Melancholy and the youngest of the vampire siblings with the nickname "Who is Coming". He is the unknown Servamp who wasn't supposed to be existed. Prior the main story, the other Servamps never heard of nor having any contact with Tsubaki, and thus, none of them knew of his existence until he introduced himself. Outwardly, Tsubaki always looks cheerful and layback, inside, true to the sin he embodies, Tsubaki is melancholic, particularly about the death of his creator whom he refers as "Sensei" and the fact that no one understands him. This led him to develop hatred for his siblings and the world, targeting his siblings one by one to fix the world that he claims to be the will of their creator. In battle, he uses a katana that capable to nullify the power of Servamp, allowing him to break their contract item. Unlike his siblings, all humans that Tsubaki changed into his subclasses are immune to sunlight. His animal form is a fox.
Servamp has an ability to change a human into a vampire by making a dying human drink their blood. This vampire is called Subclass. Similarly as a Servamp is bound to obey their Eve, a Subclass is bound to obey the Servamp who changed them.
Servamps are no without any weaknesses. Even though these weaknesses won't kill them, it's able to momentarily weaken them. So far the known weaknesses are:
- They automatically changes into their animal forms if exposed to sunlight.
- They can change back to their human form and fight during daytime if they drink their Eve's blood, but not as strong as during nighttime.
- They can't swim in flowing water.
- They'll collapse if they touch holy water for a few seconds, even if it's just a tiny drop.
- As stated before, if their contract item is destroyed, they'll lose their power.
- Sleepy Ash is the only Servamp without any Subclass.
- Old Child has the most Subclass out of all Servamps.
- Tsubaki is the only Servamp without an Eve.