|I believe in the security of the Walls...and the king...Our actions weren't misguided...or so I thought...but...So this is how much it hurts...Just torture me to death...It's all...I ever did with my blood-stained life.|
|— Sannes reflecting upon his life|
Sannes is a tall man with a short crop of dark-colored hair and bright eyes. He is usually seen wearing the Military Police uniform but is also seen wearing a white button-up shirt, black pants, and white shoes when he is tortured by Hange and Levi.
Sannes is an individual who holds a strong sense of loyalty to the king and keeping the security of the Walls, to the point of adhering to the murder and torture of others regardless of who they are to maintain peace. Like most Military Policemen, he looks down upon those from the Survey Corps, regarding them as lackeys that only waste taxes used to fund them, unlike useful soldiers such as himself. However, he has shown a degree of carelessness and did not take much caution when disposing of people viewed as threats, as seen when he revealed how he was aware of Nick's status in the Church of the Walls and how his valuables would be a motive for murder-robbery when the Minister's identity was concealed as a chair craftsman without a single piece of luggage, Sannes also left signs of torture on Nick's body and evidence of torn skin on his own knuckles.
In spite of that, even when held captive and tortured, he refused to tell his abductors his knowledge about the Reiss Family, believing that even if he were to die that his comrades would carry on their task of protecting their great king and bring down the Survey Corp's coup d'état without him. He believes that humanity was able to come this far in peace and without war was due to the efforts and sacrifices of the first squad Military Police, who would quickly murder these threats, and how people should be grateful towards their actions. Sannes has shown a degree of cruelty, admitting that he enjoyed inflicting pain upon the helpless, feeling justified of his actions since he was doing it for the greater good and thought of what he was doing as just and moral. But it is later revealed that Sannes has feelings of guilt and regret for his own actions of the past as Levi and Hange continue to torture him, crying to them that they should have fun and continue to hurt him without holding back, finally coming to realize just how much pain he inflicted on others during his life, asking to be tortured to death as compensation.
Djel Sannes joined the Military Police out of an extreme sense of loyalty and desire to serve the king. As part of the First Interior Squad, one of Sannes's main jobs was to discretely dispose of any citizens who threatened the government's reign inside the Walls.
When a young boy began talking to his friends about his father's theories that the royal government had forcibly removed humanity's memories of the outside world in order to more easily control them, Sannes apprehended the boy's father and killed him.
Sannes later met the serial killer Kenny Ackerman while attending a speech that King Uri Reiss was giving to the Church of the Walls. Kenny attempted to apologize for killing a large amount of Sannes's comrades during his time as a killer, but Sannes was unconcerned as long as the man was now loyal to the king.
Sannes is among the Military Police members who accompany Kenny Ackerman to kill Rod Reiss's mistress and his illegitimate daughter. Although they kill Alma, Rod convinces them to spare Historia by giving her an alias to live under.
After receiving word that Minister Nick from the Church of the Walls has divulged valuable secrets to the Survey Corps, Sannes and Ralph are ordered to find out how much he told. Visiting the man, the two savagely beat and torture Nick. Despite their best efforts however, Nick refuses to talk and eventually dies without saying anything.
Sannes and Ralph cover up the torture by claiming that Nick was killed during a burglary gone wrong. When Nick's friend Hange Zoë attempts to investigate, Sannes refuses to allow them entry, claiming they will interfere with the crime scene. As Hange persists, Sannes forcefully grabs their jacket to inspect which unit Hange came from, but is held back by Moblit, who properly introduces Hange and himself. Hange notes that it is odd that the First Interior Squad is investigating the crime and Sannes simply insults them before claiming that cases like Nick's are not a rarity.
Sannes and Ralph receive word that Dimo Reeves knows the location of Eren Yeager and Historia Reiss. However, en route they are kidnapped by Hange and Levi Ackerman. He wakes up tied to a chair in a room with Hange and Levi, with a tray of surgical equipment in front of him.
Hange begins to torture Sannes and the man points out that Hange has not tried questioning him. He is told that the real torture would not start until after all his nails were pulled off, with Hange breaking a finger in the process. Sannes is beaten until Hange and Levi decide that they have repaid him for Nick's death. Sannes claims that the torture and murder he participated in were necessary to maintain peace within the Walls, claiming they should be grateful for what the MPs had done for humanity. Sannes laments that the Survey Corps was not eliminated earlier and Levi begins to torture him again, asking about the Reiss family.
Sannes comments on his jailers' cruelty, noting that they seem to enjoy torturing others. He claims that he does as well and asks Hange if they feel incredible since they think they are doing something great. Although he claims to still be loyal to the king, Sannes breaks down and asks them to kill him for putting others through the pain that they are causing him.
The three torturers take a break, and Sannes is left alone. He soon hears Ralph's voice outside of his cell, and is shocked to learn that Ralph has apparently cracked from his torture, and revealed everything to their captives. Shortly after, his torturers return and a broken Sannes readily reveals to them that the Reiss family is the true royal family.
He is later put in the same cell as Ralph where he tries to strangle him for betraying the king, Hange reveals that Ralph did not talk. He was used as a means to trick Sannes into revealing everything. Hange berates Sannes for what he did before leaving. As Hange leaves, Sannes wishes them good luck and warns them that one day there will be someone to take on their role again.
After Rod Reiss is finally defeated and Historia is crowned as the queen, Sannes is seen inside a prison. His wounds have healed and he has a relaxed look on his face.
When members of the Survey Corps begin acting on their own to undermine the military, Hange is reminded of Sannes's warning that there will always be people to perform the government's role, and to play the mutineers' role.
- Ralph - Sannes's companion and friend, the pair was almost always seen together and appeared to be close. When Sannes was captured he trusted that Ralph and his companions would continue on with their tasks and bring down the Survey Corps after his death, showing concern and fear for his friend when he found it he had been captured as well. Sannes was very upset to hear his companion, blatantly insulting him about being a pain, not caring about his injured condition and asking for him to be killed, never fully realizing that was possibly never Ralph's true feelings, as he was being forced to read from a script. Upon meeting him again, Sannes attempts to choke Ralph, however, he soon learns that Ralph was forced to read from a script and it was only Sannes who revealed all the secrets to the Survey Corps.
- Kenny Ackerman - Despite the fact that they were very close to the king, the only seen interaction between them was during their first encounter, during a speech given by Uri to the Church of the Walls. Kenny sarcastically apologized to Sannes for the members of the Military Police he murdered in the past, though Sannes did not seem to hold a grudge against him; and even admired the fact that Uri made him his bodyguard despite that. Kenny noticed Sannes's infatuation with the king, and Sannes also observed that Kenny was very attached to him too. Kenny remembered Sannes during his last moments, when he thought of him and his devotion for the king as one of the reasons people live for.