Erifef

Erifef is the het ship between Eridan Ampora and Feferi Peixes from the Homestuck fandom.

Canon
Eridan and Feferi are first introduced as moirails (a type of alien romance resembling a human friendship). Eridan, however, secretly wants to be in a deeper relationship with her. During their relationship, Feferi felt that Eridan wouldn't share his feelings and she was constantly worried that he would hurt himself or others. Due to this stress, Feferi breaks off their moiraillegiance -- this leads to Eridan asking if they can become matesprits instead, to which Feferi refuses. Feferi ends up in a relationship with Sollux, but Eridan continues to pine after Feferi. This eventually culminates in him attacking her current matesprit Sollux and killing Feferi. Eventually, Eridan is also killed by Kanaya; they both are brought back as sprites.

Later, as Erisolsprite, he apologizes to Fefeta for killing half of her. She is seen greeting him in [S] Terezi: Remem8er, so they may at some point reconcile.

Fanon
Erifef is a divisive ship among the Homestuck fandom; some argue that Eridan was emotionally abusive to Feferi, or that Feferi led Eridan on. These detractors generally think Feferi and Eridan are best away from each other. Others think their relationship could be fixed and are in favor of them reuniting as friends or in a romantic relationship. Seeing them as a poly relationship with Aradia and/or Sollux is also common, due to nearly all of these characters (aside from Aradia and Eridan) having canonical complicated relationships with each other.

Fandom
Erifef posts on Tumblr

Eridan/Feferi fics on AO3