Lucifer Morningstar/Relationships

Charlie Morningstar
Charlie is Lucifer's daughter. In the pilot, it is implied that Lucifer does not believe in his daughter's plan to rehabilitate sinners. When Charlie calls Lilith to talk about her failed interview, she says, "I think Dad was right about me". Nonetheless, Charlie did take his words of dealing with demons to heart, such as Alastor.

In "Dad Beat Dad, "Charlie reveals her parents separated, and she hardly sees her father anymore. She only hears from him when he needs something. Despite Lucifer being willing to use his influence for his daughter's needs, she is hesitant to overuse that privilege. She only used it when she needed to visit Heaven's higher-ups, which tested the limits of her father's power. For the first time in years, Charlie initiated a phone call between them. Lucifer was shocked and excited when he saw his daughter calling, wanting it to be perfect. It is evident he still deeply loved her due to all his family photos, and the two share many mannerisms. He tries to come off as cool, but he awkwardly plays down how distant they've become in the present day, not knowing about Charlie's Hazbin Hotel. It's suggested he focuses more on his own problems instead of maintaining a relationship, unintentionally neglecting her. Despite having trouble expressing his affection for her, Lucifer wishes to spend more time with Charlie and desires to feel close to her as evident when he sings with joy after Charlie invites him to the Hotel.

Upon seeing her, he hugs her tightly and even threatens Razzle and Dazzle by reminding them their job of protecting Charlie. He first meets Alastor and the two get off on the wrong foot as Lucifer feels threatened by Charlie relying on him. He then meets Vaggie, Charlie's girlfriend, for the first time and hugs her with excitement before meeting the rest of the members. He and Alastor soon get into a singing match over who Charlie can receive more help from and Alastor infuriates him by insinuating he views Charlie as his own child. After Mimzy's introduction, Charlie takes her father on a tour, but Lucifer confesses he doesn't think sinners are untrustworthy and Charlie is putting too much faith in them. When they are attacked, and Alastor defends the Hotel, Charlie is upset that Lucifer doesn't believe in her or her dreams. Lucifer soon breaks down as he explains how Heaven let him down, and he doesn't want Charlie to go through the same thing. Despite their strained relationship, he ensures he will do anything to protect her from getting hurt. In turn, Charlie tells him about her memories of the stories he told her that inspired her and her determination to save their people. The two reconcile as they come to learn more about each other.

For all his failings, he is deeply caring and protective of Charlie. He will unleash his fury on anyone who dares to seriously harm her. In the season 1 finale, he shows up to fight Adam himself after he tries to kill Charlie. In the past, Lucifer feared provoking Heaven, knowing it could be worse than the annual exterminations. However, he put that fear aside to save his daughter. Despite Adam trying to kill Charlie, Lucifer still respected her wishes to spare him, knowing it was better for future diplomacy.

This is likely why the denizens of hell don't dare to harm Charlie. Despite their disrespect and insults toward their princess, Charlie's life being endangered could be one of the few things to bring down Lucifer's wrath. Outside of the Hazbin Hotel, sinners mostly refer to Charlie as Lucifer's daughter and not her first name. This implies that Charlie hasn't proven herself as an individual yet, and sinners are more concerned about her family name. Depending on the sinner, Charlie's connection to Lucifer invokes worry or intrigue.

At the end of season 1 his and Charlie's relationship is shown to have improved immensely, with Lucifer not only helping Charlie rebuild the hotel but admitting that Charlie has changed his mind and he sincerely believes in her vision now.

Lilith
In "Overture", Charlie tells the story of how Lilith and Lucifer would meet and fall in love. Together, the two gave Adam's second wife, Eve, an apple that was said to grant knowledge and free will. For this act, Charlie explains evil was born and as punishment Lucifer and Lilith were sent to Hell. Lucifer could no longer see the good in humans while Lilith thrived as the Queen. The royal couple would later have a child, their daughter Charlie and for a time, the three seemingly had a happy life together despite the constant dangers that came with running Hell.

Though little is known about their actual relationship outside of being married, they are revealed in "Dad Beat Dad" to have separated and according to Charlie, Lucifer and her drifted apart as Lilith seemingly took Charlie with her. It is unknown what caused the separation, but it is evident Lucifer continues to love Lilith greatly as he continues to wear his wedding ring and has become depressed as he works on his rubber ducks to distract him. It is unknown if Lucifer is aware of her disappearance or knows of her location.

Razzle and Dazzle
Razzle and Dazzle were gifted to Charlie by Lucifer during her childhood to act as her personal bodyguards. Razzle and Dazzle are protective of Charlie and the rest of her family.

KeeKee
Indicated as a family pet of the Morningstars, KeeKee is adored by Lucifer as he affectionately greets her while visiting Charlie.

Alastor
Lucifer does not seem to know Alastor before meeting him in "Dad Beat Dad", as he asks who he is and states that he does not know him from his radio broadcast. However, the two immediately do not get along. Shortly after Charlie introduces them, Lucifer suggests that Alastor is a has-been and insults the hotel's name. In response, Alastor cusses him out.

Additionally, Lucifer shows jealousy towards Alastor when the latter began showing off his "deep" bond with Charlie. This caused Lucifer to become increasingly insecure about his relationship with his daughter, and he began to compete with Alastor for her attention.

Mammon
Mammon considers Lucifer his "friend". Whether Lucifer affirms this friendship with Mammon is unknown.