Rebekah and Freya

 

The relationship between the sisters - Original Vampire Rebekah Mikaelson and the Witch Freya Mikaelson.

Freya is the older sister of Rebekah Mikaelson Rebekah first meet her sister in 1914 at a Christmas party Freya knew who she was but Rebekah had know idea. The two sister's reunited in the Dowager Fauline Cottage Freya helped Rebekah when she was stuck in the cottage, It was there that Rebekah learnt that she has meet her long lost sister Freya.

History
Rebekah and Freya first met in 1914 during the Christmas celebration thrown by the Mikaelson siblings (In the episode "The Map of Moments"). Freya wanted to meet her siblings. Rebekah thought that Freya was Kol's lover and she warned Freya.

Throughout The Originals series
In Gonna Set Your Flag On Fire, Freya communicated with Rebekah. Rebekah didn't know, who was trying to communicate with her. Rebekah just saw a mystery black-dressed girl in a coffin.

In Sanctuary, Freya is being beaten by The Kindred, Rebekah notices the beating and steps in to help Freya. Rebekah is punished as a result of this and Freya's necklace is taken. Later, Rebekah wanders into the locked room of the Dowager Fauline Cottage, when inside she is attacked by members of the Kindred. Rebekah is rescued when Freya steps in and uses magic to execute the members of the Kindred and also Cassie. Freya reveals that they are sisters and helps Rebekah escape the cottage using magic.

Freya also asked Rebekah to inform their siblings that she'll be making her presence known soon and that she expects them to be on their best behavior, as any eldest sibling would. After she informs Rebekah of this, she reverses the spell on the cottage and uses her powers to ripped the gate open and walks right through the front gate.

In Save My Soul, They're happy to see each-other again for the first time since they escaped the asylum together. After being told of the "Eva problem" she promises to help her little sister, but Klaus stops that seeing as he doesn't trust Freya. Rebekah tells Klaus that Freya is their sister and shows that she trusts her citing their time together in the asylum despite not growing up together as sisters usually do.

In Night Has A Thousand Eyes, Rebekah works with Freya in an attempt to pinpoint Dahlia's whereabouts. When Hayley sees that Dahlia is channeling Freya's power, everyone is immediately on their guard against Freya, despite her adamant claims that she is not allied with Dahlia. Rebekah apologizes to Freya, but reluctantly admits that it would probably be best if she left the compound.

In When the Levee Breaks, Freya is mourning their father Mikael in the cemetery. Although unhappy with their brother Klaus, Rebekah still defends him despite Mikael's murder. Freya does not understand why Rebekah remains so loyal to Klaus, and subsequently demands that Rebekah choose between the two of them. Later, Rebekah confess to Marcel that she cannot choose between them - but state that she always wanted a sister.

Trivia

 * Freya describes Rebekah as someone with a spark inside of her, willful but also kind. Freya reassured Rebekah that she was not even half as bad as their brothers.
 * Unknown to Rebekah at the time, they first met at a Christmas party in 1914.
 * Freya seems to play the protective older sister since meeting Rebekah. She not only took down the people in the Cottage seeking to hurt Rebekah, but also healed her broken hand and broke her out of the asylum.
 * Both are Mikael's favorite children seeing as he favors his girls over the boys
 * Unbeknownst to Rebekah, Freya plans on turning her against their brother, Klaus.
 * Freya seems to prefer Rebekah's company over her other siblings because she shares Rebekah's same sentiments of having a sister.
 * Freya is the oldest daughter and Rebekah is the youngest daughters while it was thought for years by the viewers that Rebekah was the only girl in the family.
 * They bear not only a strong resemblance to each other, but to their mother Esther as well.