Half-Genies are the offspring of Genie mothers and human fathers. All the ones seen so far have been female, and they do not possess the full powers of their Genie lineage. In spite of their lack of skills, the daughters of the Genies made a decision to pool their powers and stand against evil as best they could. Few and far between, these Half-Genies traveled the land, each choosing a kingdom to guard until peace could be won again. As they struggle to keep the peace, new villains emerge and ancient foes return to wreak havoc on Sequin Land.
It's mentioned in the first game by an unnamed NPC that Half-Genies are often born with unusual powers, such as one unknown and unseen Half-Genie being able to shoot milk out of her eye. Shantae's (unusual) power is magic bellydances which help her achieve various feats, including transformation into various creatures or teleportation. She also can use her hair as a weapon, but it is revealed at the end of Shantae: Risky's Revenge that it is her own unique ability, as she can still use it despite her lack of Genie magic.
While the existence of multiple Half-Genies is implied as early as, Seven Sirens is the first time any Half-Genies aside from Shantae are seen.
Harmony, Zapple, Vera, and Plink make their debut, visiting Arena Town for the Half-Genie Festival alongside Shantae. Vera is a resident of the island, and guards Tree Town. Zapple is implied to be Armor Town's guardian genie. Plink and Harmony's homes are never specified, but the Ghost Genie's presence may indicate that Harmony has some history with the island.
According to Harmony, there is only one generation of Half-Genies, as they have not been around for that long. She further explains to Shantae that their kind will eventually go extinct if the genies (including Shantae's mother) do not return.
- If you talk to the Ghost Dog/Genie after gaining the Quake Dance she asks how Shantae gained such a power as only she and her daughter have that ability, which implies that Harmony is the daughter of this ghost. It also implies all Half-Genies inherit the same exact magic type as their mothers, and that each family has a specific magic type that is exclusive to them.
- While the Half-Genies' ages aren't specified, Harmony is stated to be the oldest, and Shantae is the youngest according to the Mayor of Arena Town.
- Harmony and Shantae are the only Half-Genies with recorded lines from their correct actress. Zapple only has three lines from Cristina Vee, and Erika Ishii, her true actress, as well as Laura Stahl and Kayli Mills, only did grunts for their respective Half-Genies, as their lines were only written in text boxes.