Erifef

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

Canon
Eridan had a flushed crush on Feferi, but apparently, he didn't play his cards right (as he implied in a conversation with Kanaya and then later admitted to Feferi herself), leading to Feferi refering to Eridan as her moirail, in lieu of the romantic relationship he would have preferred, but during their relationship, Feferi constantly worries about getting out of line due to her spending all of her time worrying about him and trying to keep him from committing genocide or hurting himself, and she expressed frustration at his reluctance to talk about his feelings or listen to her own. Eridan, for his part, helped her feed her lusus and didn't kill all of the land dwellers because he knew it would upset her.

After Feferi's entry into the medium, she terminates her moirallegiance to Eridan as a result of Eridan's overbearing and taxing nature. This devastates Eridan, although he takes the chance to ask Feferi about them becoming Matesprits instead, which she promptly refuses as well.

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, yet complicated relationships with each other.

Fandom
Erifef posts on Tumblr

Eridan/Feferi fics on AO3