In volume 5, Hazel fights alongside Mercury and Emerald during the Battle of Haven. But after they seemingly lose both Cinder and the Relic of Knowledge, the three of them are then forced to retreat. Without Cinder to lead them, Emerald sticks close to Hazel after them and Mercury escape Haven. Hazel then carries an unconscious Emerald after she overtaxes herself from using her Semblanceon too many people.
When they return to Salem's palace, him and Emerald exchange a quick knowing glance before exiting the tranaport. He then tells Emerald and Mercury to ignore Tyrian's taunts and proceed inside. When Salem asks who is responsible for their defeat, Hazel initially takes the blame on himself in order to deflect it away from Emerald and Mercury, thinking they might get hurt. After Salem nearly kills Hazel for taking the blame for their haven academy failure, a terrified Emerald then admits to Salem that Cinder isthe one responsible for their defeat at Haven Academy. From this, it appears that Hazel is quite protective of them, especially Emerald, and the two seem to trust each other enough to work together.
Later, in volume 6 when Salem orders everyone to clear out the council chamber, Hazel urges Emerald to comply by putting a hand on her shoulder and leads her outside. In volume 6 chapter 13, as Mercury and Emerald watch Salem create a new Grimm army, Hazel explains that she intends to do battle herself. In volume 8 chapter 7, both Emerald and Mercury are shown to have a strong sense of respect for Hazel. This is seen when Mercury stated that he was a example that he and Emerald should follow in regards to their affiliation to Salem. In volume 8, when Hazel and Emerald learn ghr truth about Salem they both plan to escape together. Hazel then saves Emerald when Salem almost kills her. He then sacrifices his life in order for Emerald to escape with her own life.
Sister complex is a rarepair in the rwby fandom. Mostly because there is quite a huge age gap between these two. Also some people prefer to think of the two as having a brother-sister or father-daughter relationship. Fans were extremly satisfied when Hazel sacrificed his life for Emerald. It has a small fanbase on tumblr.
- Their ship name comes from the fact that Emerald reminds Hazel of his sister Gretchen, hence why he has a "sister complex".