Natsuki Subaru/Relationships

Emilia
Subaru falls in love with her at first glance. He devoted himself to protecting her no matter what happens to him, even if that meant having to repeatedly go back in time by dying. Initially, she does not understand the meaning of his playful flirting with her, but gradually she nevertheless develops reciprocal feelings for him and even becomes jealous if she sees his "interest" in other girls. Their relationship is one of the main themes of the series and, in fact, the main reason for Subaru's development as an individual, because thanks to her, he gradually gets rid of his impulsive personality and learns to be more reliable, judicious and useful person than he was at the beginning of the novel. Later Subaru officially becomes her Knight which symbolizes the strong bond of trust she has developed towards him.

Satella
Satella is the one who granted Subaru Return by Death and also stands behind his summoning to the new world. Originally, Subaru harbored intense hate and fear for the Witch but upon finally meeting her face to face in the Witches' Tea Party and coming to understand her intence emotions with the help of Carmilla's Authority of Lust, Subaru promised her that one day he'll find her and save her no matter what, despite Satella's initial request to kill her. In the prologue of the 9th volume, Subaru shows mutual and intense feelings for Satella which gradually turned into (and were described) as representing each of the seven deadly sins, starting from sloth and ending with jealousy.

As already mentioned, The Witch of Envy stands behind Subaru's Return by Death. Whenever Subaru breaks "their promise", Satella preforms some type of punishment, either by crushing his heart or (in extremely rare occasions), crushing the hearts of people he cares about the most. In arc 6, Satella repeatedly caused the destruction of the Pleiades Watchtower and killed everyone in it, as long as Louis Arneb was latched onto Subaru.

Rem
After starting out initially as enemies, Rem eventually comes to fall for Subaru after he ends up saving her emotionally and physically during the events of Arc 2, where afterwards she begins devoting herself to him. After she confesses and wins over a part of his heart after her numerous efforts to support him in Arc 3, Subaru agrees to take Rem on her polygamy offer only if Emilia allows it, and make her his second wife. In Arc 4 he admits to Emilia that he loves them more or less equally, though Emilia remains still first for him. Subaru was heartbroken to discover that Rem had fallen into a coma and that not even his Return by Death could save her. However, he presses forward knowing that would have been what Rem would have wanted him to do and in the hope that he can one day free Rem from her slumber.

Beatrice
Subaru and Beatrice initially had an antagonistic relationship. Subaru's personality often annoyed Beatrice, leading her to always mock and insult him. Subaru however begins to rely on Beatrice for knowledge and advice and exclaims how close they are. While Beatrice's actions imply the friendship is one-sided, she does to an extent care for Subaru as she cured him of his curse and foretold him about his death and how he could avoid it. She willingly made the contract to protect him from any potential threats to his life and defended him from Ram and Roswaal's attacks post Rem's death. After she became his Spirit partner, she starts to open up.

Ram
Ram has a rather amicable relationship with Subaru despite the constant disparaging remarks she throws at him. During his time as a butler, she was in charge of teaching him about their daily duties. She even took the time to teach him how to write so he became more accustomed to life at the manor. Ram was also the first person to vouch for his character when it came to the possibility of him being a spy even when his past was still virtually unknown. Despite harshly assessing his skills as a butler, she nevertheless held a sense of fondness for him as her junior colleague. Ram would later come to trust Subaru's intuition even if the likelihood of the scenario had no basis due to his unexpected successes. Although they both hardly mention it, they both care very much for each other's well-being and they are both good friends.

Puck
Subaru has a positive friendship with Puck, likely stemming from the boy's friendship with Emilia. However, in a loop where Subaru accidentally killed Emilia by telling her about Return by Death, Puck angrily froze him to death for breaking his promise with Emilia, returning to the mansion against her wishes, and being the one that killed her.

Roswaal L Mathers
Subaru was originally impressed by Roswaal, admiring him as the head of the Roswaal mansion and Emilia's primary benefactor despite the wizard's eccentric behavior. After the event of Arc 4, he realized that Roswaal is actually an egoistic and cruel person dedicated solely to reviving his master. Among Subaru's allies, he is the first to figure out that Subaru is looping through some method. After Subaru defeated Roswaal in their challenge, Roswaal has agreed to help him but has also threatened to force Subaru into undergoing another loop if he makes a mistake.

Otto Suwen
After Subaru saved Otto from financial ruin, and offered him a job as the minister of interior affairs for the Emilia Camp, the two of then have become steadfast friends. Though their relationship has involved Subaru lightheartedly teasing Otto, the two of them are still rather loyal to each other, with Otto always having his best interests for Subaru in mind.

Garfiel Tinsel
Subaru helped Garfiel to understand the truth about his mother and became good friends with him. Despite his fights in the past, Subaru was still willing to talk to him. Their relationship eventually blossomed to that of a loyal subordinate and his captain, their camaraderie tied by not only that but also deep friendship.

Reinhard van Astrea
Upon first meeting Reinhard, Subaru immediately recognized him as someone who has been chosen by God himself. Originally jealous of his gallantry and manliness, Subaru did not waste much time and started his soon-to-be-necessary relationship with him on a good note. As it later turned out, Reinhard's presence was vital in overcoming the Loot House incident and defeating Elsa while saving Emilia's life and returning her stolen Insignia. Despite being better than Subaru in every way imaginable, Reinhard considered Subaru to be his equal; even more so after Subaru defeated the Hakugei, liberated the Sanctuary and played a vital part with retaking of the Watergate City of Priestella, having been the key card in taking out the Sin Archbishop of Greed.

Currently, both Reinhard and Subaru harbor immense respect towards each other, with both of them swearing to each other that they'll fill the other party's shortcomings; Reinhard will play the role of a sword and Subaru will play the role of the tactician. They both consider each other as good and reliable friends.

Felt
Subaru met Felt in the first loop when some thugs assaulted him but Felt didn't help. Later on, she was about to get killed by an assassin but got saved by Subaru. From there they both established a friendship. Sometime later, when they met again in the capital, Felt showed that she was still making fun of him. Despite the confidence they both have, Felt doesn't like to approach him.

Crusch Karsten
Subaru has fostered a good alliance with Crusch after the success of killing the Hakugei, with Crusch even giving most of the credit of the victory to him. After her memories got eaten by Ley Batenkaitos their relationship became somewhat neutral. However, after the events in Arc 5 at Priestella, they regained their friendship after Subaru accidentally saved her by taking in the part of the Dragon Vein that Capella used to poison her.

Anastasia Hoshin
Subaru and Anastasia's relationship is somewhat complicated. In one loop where Subaru accidentally told information about Crusch's Camp she abandoned him after revealing that she was actually using him. Despite this, Subaru still saw her as a key potential ally alongside Crusch during the campaign to subjugate the Hakugei. Currently, their relationship hasn't improved, because Anastasia is currently possessed by Echidna.

Julius Juukulius
Subaru and Julius started with a bad relation when Subaru forgot his place. While both have apologized to each other after the battle with the Hakugei, Subaru told him he still hated him, with Julius stating that he didn't think they could be friends. After Julius' name got eaten by Roy Alphard, their relationship has gotten somewhat better and became close friends with both liking each other during their trip to the Pleiades Watchtower.

Ricardo Welkin
Subaru first thought of Ricardo as an annoying guy that would give him a headache. Gradually, Subaru realized that Ricardo was looking out for him, calming his nerves before the battle. Subaru's first impression of Ricardo has changed since then. During the fight against the White Whale, he saved Subaru by taking the hit and sustaining major injuries in the process. In exchange, he gives Subaru a message which in turn helped Subaru realize the catch behind the Hakugei's trick which allowed Subaru and Crusch to develop a plan and take the giant beast down.

Echidna
Echidna is greatly interested in Subaru's Return by Death ability, as it allows him to collect information from multiple points in time. To that end, she invited him to her tea party so in order to strike a conversation with him and later offered Subaru her assistance in the form of a contract. However, Subaru rejected the offer after the other witches gave hints that Echidna wasn't telling the full truth, noticing that she is actually using him. After the other Witches helped Subaru realise how Echidna's only goal was to use him as a lab rat, he decided to cut all ties with her. His opinion of her is the same as his opinion of Roswaal.

Meili Portroute
After the death of Elsa Granhiert, Meli was captured and was overseen under the Roswaal manor. Subaru forgave her and gives her a panda to convince her to help him from now on.

Lye Batenkaitos
Even though Subaru doesn't know Lye that well, he feels immense anger towards him for placing Rem in a coma and stating that he will avenge her. Lye sees Subaru as his savior as his Return by Death will allow him to experience tastes and memories like no other.

Regulus Corneas
Subaru confronted him during his and Emilia's wedding in Priestella, which led to a battle that Reinhard joined in on and concluded with Regulus' death. Regulus and Subaru started off on a rather respectful note, but they soon after exchanging a couple of words, they both started to strongly resent each other; Subaru's dislike stemmed from Regulus' abduction of Emilia while Regulus finds fault in Subaru's talkativeness and him disregarding his opinions which, which for him, meant that Subaru was belittling his rights, therefore he must be punished appropriately.