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.

Rem
Subaru relies on Rem for emotional support after fighting with Emilia.

Satella
After Subaru met Satella for the first time, she asked him to kill her but he said he will save her instead of killing her. Even though Satella is deeply in love with Subaru, he hasn't the same feelings as he has for Emilia.

Pack
Subaru has a positive friendship with Pack, likely stemming from the boy's friendship with Emilia. However, in a loop where Subaru accidentally killed Emilia by telling her about Return from Death, Pack 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.

Beatrice
Originally, Subaru found Beatrice cute but very cruel and annoying. However, after they she became his Artificial Spirit, she became less cruel and started to understand Subaru's feelings.

Crusch Karsten
Subaru has devolped a good friendship with Crusch after the succes of killing the Hakugai. After her memories got eaten by Ley Batenkaitos their relationship became some what neutral but after the events in Arc 5 at Priestella they got a better friendship. Capella Emerada Lugnica poisoned her but Subaru took accidently a part of the Dragon Veins within himself and accidently saving her.

Anastasia Hoshin
Subaru and Anastasia's relationship is somewhat complicated. They talked normal to each other and saw each other was partners. However, in a loop where Subaru accidentally told information about the Crusch Camp she left him, revealing that she was actually using him. Currently their relationship hasn't improved, because Anastasia is currently possessed by Echidna

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.

Roswaal L Mathers
Subaru was origianlly impressed by Roswaal. He thought he was a hero and knew him as the head of the Roswaal mansion. After the event of Arc 4, he realised that Roswaal is egoistic and is a cruel person. As he figured out that Subaru is looping through some method, causing him to challenge him, and subsequently lost. Though he has agreed to help him after losing, he has threatened to force him to loop if he makes a mistake.