Relationship between Vax'ildan and Vex'ahlia

As siblings, Vax'ildan and Vex'ahlia are very close. They were very upset when they had to be separated during the "Trials of the Take" for membership in the Slayer's Take guild.

When Vax was near death during their first encounter with the Briarwoods, one of his final thoughts revealed that he considered Vex to be his best friend. As her brother fell unconscious, Vex immediately felt a sense of dread and took off running, following her previously-placed Hunter's Mark to the Briarwoods.

When Vex suddenly died from a trap in the tomb of Purvan Suul, Vax was devastated. During the ritual to revive her, the Raven Queen herself began to appear, and Vax told her to "take [him] instead". The Raven Queen apparently agreed, as Vex'ahlia was successfully revived and Vax'ildan became the new Champion of the Raven Queen.

Vax was nervous and scared about his new position as Champion, so Vex did some research into the Raven Queen in order to reassure her twin that she was not an evil deity.