|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' 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 her entry, claiming she will interfere with the crime scene. As Hange persists, Sannes forcefully grabs her jacket to inspect which squad she came from, but is held back by Moblit, who properly introduces Hange and himself.
Realizing that both soldiers are from the Survey Corps, Sannes turns hostile and insults them. Hange is shocked to find a soldier from the First Interior Squad where they have no jurisdiction. Sannes explains to them that this area was very important and he was stationed there because there were not enough soldiers around.
Sannes claims that what happened to Nick is not rare, considering his status. Hange pretends to be surprised and lies about Nick but Sannes dryly interrupts her. The latter apologizes, entrusts the investigation to the two men and asks them to relay a message to the culprits before leaving.
Sannes and Ralph are later seen being led, on a horse carriage, to the location where Eren and Historia are being held by Dimo Reeves, unaware that they had been given false information and were betrayed. According to the plan, the horse slips and the carriage along with Sannes and his partner fall into a deep trench. It is shown that Hange and Levi caught Sannes and Ralph before they fell to their deaths and brought their unconscious bodies back to their hideout. 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, pulling off all his fingernails in retaliation to what he had done to Nick. Sannes protests in pain and asks why was he tortured without being questioned. 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. Levi begins to start punching Sannes in the face until he deems that they had done everything he had done to Nick, breaking his nose and causing his right eye to swell shut. Hange then shows the captive all his pulled off nails and apologizes for not being as skilled as him. Sannes responds by saying that the torture and murder he did or witnessed were necessary to maintain peace within the Walls, taking the examples of Erwin's father, Armin's parents, a weapons inventor, and Historia's mother. He yells at them to be grateful for what the MP had done for humanity, only to receive a dull and sarcastic response from Hange. Sannes expresses how he wished that the Survey Corps had been eliminated earlier and how they were the biggest pests threatening their peace. Levi begins to torture him again by twisting his nose and questions Sannes about the Reiss family.
Taking too long to answer, Hange pulls out one of Sannes's teeth as punishment. With tears in his eyes, Sannes comments on his jailers' cruelty before screaming at them to have as much fun torturing him as they want because they seemed to love violence so much. He claims that he does as well, telling them to keep having fun at his expense and that they had no need to hold back since what they were doing was just. He then asks Hange if they felt incredible since they can think of themselves doing something great. Sannes calls Hange and Levi monsters and adds that they do not scare him, professing his devotion to the king and his faith in his companions, before breaking down in tears asking them to just torture him to death as he begins to doubt if his actions of the past were really for the greater good.
Hange and Levi leave the room to take a break and Sannes lets go of his bladder. He realizes that this is the end for him but trusts that his comrades would find a way to sort this out. He then hears Ralph's voice from outside the door and he fears that Hange and Levi were going to torture him as well. He manages to overhear their conversation and learns that Ralph had told them everything after only losing a nail. Ralph also adds that none of them liked Sannes and that Hange should kill him for good. This deeply hurts Sannes and he soon falls asleep.After finishing with Ralph, Hange and Levi get back to Sannes, who cracks and reveals 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 without hesitation but is stopped by Hange who tells him that Ralph had not revealed any information but was instead used as a means to have Sannes reveal everything. This causes Sannes to call Hange and the others demons, with Hange replying that Nick surely thought the same of his murderers and yells at Sannes to blame himself for his current state. Crying, Sannes wishes Hange good luck, but also states 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.