We Are The Night

Aboard a private aircraft, the pilots and passengers all dead, with bites to their necks. The killers, three women, preparing to leave, the leader of the three finds an air-hostess still alive, but after examining her eyes, she breaks the hostess' neck and the women jump out of the plane, allowing it to crash. In Berlin, a young criminal, Lena, lurks near a cash dispenser. Just as her victim has used the machine she pickpockets his credit card, but moments later her mark is arrested by the police. She flees, but a police officer, Tom, chases after her and eventually catches up with her on a bridge. After a short conversation, he tries to arrest her, but Lena hits him in the face, kicks him between the legs and jumps off the bridge onto a passing boat.
Later that evening, Lena goes to a nightclub, which is run by Louise. Inside the club, Louise dances with Lena and offers her a drink. When Lena goes to the bathroom, Louise follows and bites her. The terrified Lena runs home. When she awakes in the morning, the sun burns her, forcing her to stay inside. That night, Lena returns to the club to confront Louise about what has happened. She meets Louise's two companions, the stoic Charlotte and the cheerful Nora. On Charlotte's suggestion, the women sell Lena to some Russian pimps to force her to accept her new state of being (the word "vampire" is never mentioned in the film). Lena attacks one of the mobsters as the tries to rape her, but she is shot by another pimp wielding a shotgun. The women enter the compound, killing the criminals, then set them ablaze, but fail to notice one mobster hiding in fear. Before leaving, Nora steals one of the mobster's Lamborghini. Coincidentally, Tom is assigned to investigate the murders, and he discovers a hidden video camera, which has recorded the attack, and, although the women cannot be filmed, the video does show the surviving criminal.
When Lena awakes at the hotel, Louise gives her a glass of what appears to be blood. As Lena drinks, she feels her strength return. Louise bathes Lena and tells her the story of how she was changed. 280 years ago at a masked ball. At first she hated her maker, but grew to love her after traveling throughout Europe and getting to know all the benefits of the immortal life. After her maker was killed by sunlight, Louise wanted to commit suicide to join her, but instead began searching for a new companion. As Lena bathes, her short hair grows and returns to its natural color, her piercing falls out and she loses all bruises and wounds (including a tattoo on her belly).
Lena spends a night shopping, partying and having fun with the women who give her the stolen Lamborghini. As they shop, Lena notices that Charlotte longingly staring at a pair of baby shoes, and shows other signs of depression and self-harm, including burning her own eyeball (which immediately heals) during dinner at an expensive restaurant. As the night comes to an end, the women return to their hotel to perform their morning ritual: allowing the first rays of sun burn their skin but retreating inside before any lasting harm can be done. Charlotte stays outside longer than the others, but retreats before catching fire. Louise kisses Lena, which startles and confuses Lena who bites Louise's lip, before she interrupts herself and begins cursing her hastiness.
The next night when Lena returns home to pick up some belonings, she is meet by Tom, who used a file on Lena to find her home address. The two have coffee and talk, but when Lena suddenly sees Louise approaching, she uses her Lamborghini to retreat to the nightclub. She finds Charlotte in a private room where Charlotte tells Lena that she was a silent movie actress in the 1920s and that she had a husband and daughter. Louise enters the room and asks Lena why she is acting different. Lena lies that she misses the sun, so Louise takes the girls to Tropical Islands Resort that has artificial sunlight allowing them to have a pool party "in the sun". Two night watchmen find the girls and ask how they managed to get inside. Nora convinces the men to join them in the pool where she quickly kills off one of them, but the other tries to escape. Charlotte kills this man in a sadistic manner, slicing his throat with a piece of paper which causes him to die slowly and painfully. Lena flees the scene in terror.
Tom and his partner, Lummer, interrogate the surviving mobster who says that the devil killed his friends and stole his Lamborghini. As van Gogh describes it Tom realizes that the stolen car is the car he saw Lena drive. The SEK (German SWAT unit) is invades the hotel. Charlotte stays to stall them while Lena, Louise &amp; Nora make their escape in special cars with tinted windows to protect them from sunlight. The police are slaughtered by Charlotte, but Tom manages to shoot Charlotte before she attacks him, causing her to fall out the window. Lena and Louise manage to get her inside their car. Nora's car crashes into another car and is thrown into sunlight and dies. The roof of the other car is ripped off by a roadblock and Louise crash into a subway to escape the scourging sunlight.
The three remaining women hide at the abandoned Teufelsberg (The Devil's Mountain) where Louise has kept cash and prepare to flee to Russia. Before leaving, Charlotte demands to see her elderly daughter. At the retirement home Charlotte sings a lullaby to her dying daughter whom in her last moments recognizes her mother but thinks her mother is an Angel being the exact age to help her cross over upsetting Charlotte. With a whole day before their departure to Russia the girls return to their hideout to perform their morning ritual. As the sun rises, Charlotte locks Lena and Louise inside and allows the sun to kill her.
Lena goes to Tom to say good bye and forces him to shoot her and the wound heals in front of his eyes to show her true nature. Lena begins to cry while Tom holds her and they fall asleep. Lummer, who has suspected Tom of having some involvement with the women since the hotel attack, has the SEK incarcerate them. Louise goes to the watchmen while they're in the shower and kills them (a deleted scene shows director Dennis Gansel playing one of the policemen getting killed). Louise ask Lena through an intercom how she would manage to live with a man destined to die, herself knowing the pain of losing a loved one. Louise kidnaps Tom and Lena follows her. At Teufelsberg, Louise wants Lena to tell her, "I love you". Lena does so and Louise says that that's the most beautiful lie she's ever heard and shoots Tom. Louise and Lena have a fight and Lena throws Louise into the sunlight, where she dies with a peaceful smile. Lena runs to Tom and wants to bite him, but stops, kisses him and begins to cry.
At the end the SEK arrives with Lummer. Lena and Tom are gone with no trace other than Louise's gun. Lummer looks outside and sees something the other policemen and the audience don't. Lummer whispers Good luck and walks away from the scene.

Question: What is the relationship between Tom and Lummer?
Answer: Partners