Since the two were young, Elsa and Anna have always been the best of friends and loved each other dearly. The two enjoyed playing together, and Anna loved it when Elsa used her magic to create a winter wonderland. However, after Elsa accidentally hit Anna with her ice magic and almost killed her, Elsa became too scared to go near Anna out of fear her powers could harm her again, even when she later became all the family she had left when their parents died. While Elsa's desire to stay away from Anna was out of her love for her, Anna felt distanced from her and constantly tried to reconnect with Elsa without understanding or knowing about Elsa's powers, as the troll king removed all magic including memories of magic to revive her. During the coronation party, the two seemed to temporarily reconnect as they enjoyed themselves and Anna expressed her wish that they could always be close like this. Elsa, caught up in the moment, sincerely agrees but knows why they must keep their distance and closes herself off again, which they are both saddened by, though Anna was not aware of Elsa's feelings. They also seemed to reconnect by their love of chocolate, after Elsa saying what is that amazing smell and they both sniffed the air to the delight of finding it was chocolate.
When Elsa's powers are revealed to the kingdom after the two got into an argument about Anna's engagement to Hans and how Elsa always shuts everybody out, Elsa runs away and Anna, knowing it wasn't Elsa's fault as she was the one who pushed Elsa, volunteered to get her back, saying "She's my sister. She would never hurt me." When she got to Elsa's palace, she tried to get Elsa to come back home with her and fix the eternal winter Elsa had cast on the kingdom together, but couldn't persuade her as Elsa didn't know how to fix what she had done and was too afraid of, and distressed at, hurting others. Elsa's negative emotions explode unwillingly, striking Anna's heart. Nonetheless, Anna's love for Elsa prevailed and proved to be the thing Anna held most dear to her, shown best when she chose to not get saved by Kristoff but instead ran in front of Elsa to protect her from Hans' killing strike, freezing to solid ice and sacrificing her own life in the process.
This demonstrates just how deep Anna's love for Elsa is and that no matter what happens, their sisterly bond is the most important thing to her. This act of true love is also ultimately what saves Anna from Elsa's curse, as Olaf makes the connection that Anna's actions were an act of true love, which teaches Elsa how to finally thaw winter and control her powers, allowing her to restore her bond with Anna. Elsa and Anna truly care and love each other and while Elsa was too scared of hurting Anna to get close to her and Anna was at times somewhat pushy and insistent on helping Elsa (which could at times make things worse) the two will always love each other and do anything for the sake of the other's happiness.
In the short sequel Frozen Fever, Elsa is excited to celebrate Anna's birthday and plans to make it a perfect, meaningful, unforgettable moment in hopes of rectifying their hardened past and to show her how much the two mean to each other. While spending the day with Anna, Elsa catches a cold, and Anna becomes increasingly concerned for her sister's health as it worsens. After getting Elsa to admit she indeed has a cold, Anna decides to put the day on hold so that she can care for Elsa.
Olaf was based on a snowman Anna and Elsa created when they were young and has a powerful connection with Elsa, as he is not only her living creation, but also the physical representation of Elsa's happiness and desire to be with her sister again like they were when they were children. Thus, Olaf's desire for summer is Elsa's desire to rekindle the warmth between her and Anna. Olaf describe her as the most nicest, gentlest and warmest person ever. When Elsa first saw Olaf alive, she was surprised, as she did not know she had imbued her beloved snowman with life. At first Elsa was happy, as he reminded her of the fun that her powers once brought the two sisters, but this also brought back the painful memory of how the fun times came to a tragic end when Anna was hurt by Elsa's powers. As a result, she tried to isolate herself from Olaf and Anna again to keep them away from her and her powers, but due to the latter's persistence, she had to use force by creating Olaf's younger "brother" Marshmallow to throw them out of her palace.
However, Elsa saw the error of her ways when she realized how powerful her bond with Anna was, as Olaf was the one to realize that Anna's act of true love for Elsa thawed her frozen heart. Thus, Elsa learned that love was the answer to ending Arendelle's winter. When Olaf started to melt, due to the return of summer, Elsa saved his life by rebuilding the almost-puddle snowman and giving him his own flurry to keep him cold. In the end, he enjoys summer and helps Anna to skate with Elsa, much like when the three skated together in their earlier years, showing that Olaf loves both the sisters.
Although she had little interaction with Kristoff (including after she struck Anna in the heart with her powers, and at the ending), it is enough to show that although she was scared and wary to see him at first, as she was with pretty much everyone else, she soon comes to accept him after knowing what he did for her sister. When Kristoff attempted to confront Hans for trying to kill the two sisters, Elsa seems touched by Kristoff's protectiveness over her and Anna. She even gives him the title "Official Arendelle Ice Master and Deliverer," so he can be with Anna. In the storybook app of the film, it is revealed that Elsa approved of Anna and Kristoff's love for each other.
And in the storybooks taking place after the film, it is shown that Elsa and Kristoff have a very good friendship, which is made stronger by their love for Anna and also for ice.
In the short Frozen Fever, Elsa and Kristoff are shown to have a bond following the events of the film, with Kristoff partially acting as Elsa's confidant.
Although Elsa and Pabbie's interaction was brief, the wise troll's words of wisdom stayed with Elsa for the years leading up to her adulthood and coronation. The encounter between the two proved to be some of the most influential of Elsa's life, eventually leading to her isolation and understanding that, while her powers are indeed a beautiful gift, it can be very powerful and dangerous, should her control over them be lacking in any way. However, like the King and Queen, Pabbie's words weren't completely understood, as the troll stated fear would be Elsa's enemy. Whilst Elsa and her family believed it was the fear others would have, Pabbie truly meant Elsa's fear, as her emotions control her abilities. Being somewhat ancient, and highly mystical, Pabbie also holds the most knowledge and understanding over Elsa's mysterious powers, more so than any other character in the film.
Unlike Olaf, who was created by Elsa's happiness, Marshmallow was born out of Elsa's desire to be alone for Anna's safety, and his existence exhibits a hostile side to Elsa's nature. Elsa, fearing confrontation, had reluctantly created him when Anna refused to leave her even after she was accidentally harmed by Elsa. Although Marshmallow had excessively forced Anna and her friends out, he returned to Elsa's side loyally and took his role as her defender quite seriously. He had even tried his best to defend her when the palace, and by extension Elsa within it, came under attack. Elsa had watched Marshmallow fight the invaders, possibly out of concern that Marshmallow would not be able to keep them away from the palace. However, as other guards had swarmed into the palace and forced her to retreat, Marshmallow risked his own life to prevent other soldiers from getting in, but had fallen into the gorge in the process. Marshmallow survived this and returned to find Elsa's palace empty (after the events of the film had taken place), yet also found Elsa's tiara and donned it, which had a calming and positive effect upon him.
- “As heir, Elsa was preferable, of course. But no one was getting anywhere with her.”
- ―Hans explaining his original plans to Anna during the betrayal scene
Inadvertently and without knowing it, Elsa and her nature as a winter elemental has been a major obstacle to Hans' pursuit of becoming Arendelle's sole monarch. Originally, it was Hans' plan to marry the soon-to-be queen regnant of Arendelle so he could rule the kingdom with her by his side. However, he gave up on the idea when he got word of her dislike of being near people. It was unknown to him that she was doing this to keep her subjects safe from her unstable winter magic. He did not learn of her abilities until she and Anna got into an argument about Anna and Hans' engagement. The instability of her emotions, caused her to inadvertently reveal her powers to everyone at the ball. From then on, as each event unfolded unintentionally thanks to the Snow Queen, Hans had to constantly change his plan to become King of Arendelle. This includes making the Queen seem like a monster in the eyes of the public, then killing her to end her accidental winter curse and become a hero of the people. His pursuit of the crown would be complete without having to marry Anna. This is also how he backed up Anna's claim about Elsa's innocence and dismissed the Duke's about the queen being a monster when she ran away and accidentally unleashed a winter curse on the kingdom, when her powers were revealed, this was done to further get into Anna's good graces.
This also required getting into Queen Elsa's good graces by stopping her from killing the Duke of Weselton's thugs after they provoked her into an angered state and appearing to show mercy towards her, when it was ultimately to get her to let her guard down for a chance to kill her with the chandelier, and locked her up in the castle dungeon and chained her down in shackles, then again after he lied to her about Anna already being killed by her accidental curse when chasing her out to the frozen fjords. However, Elsa was saved from his treachery by Anna and his plot for usurpation was foiled.
Originally, the Duke of Weselton was polite to Elsa, even offering her a dance at the coronation, but this was all to exploit Arendelle's riches in trade. When her powers are revealed to everyone, he is the first to call her a monster and continued to believe so, even though Anna and Hans tried to reassure him that she was not and was just scared. When Hans goes off to find Anna, the Duke volunteers his henchmen and tells them that if they encounter Queen Elsa, they are to kill her, which they try (and fail) to do so. When Hans told him and the other Dignitaries (as one of his lies) that Anna had died from Elsa's magic, the Duke showed some sadness over Anna's alleged death and was the first to say that there was no doubt that Elsa was a monster and that they were all in danger. At the end of the film, Elsa cuts off all ties with Weselton due to the Duke's persecution of her.