|“||Let me kill her! She slew Fal! Let me cut her throat!||”|
–Ethna desperate to avenge her brother, Lord of Shadows
Ethna was a daughter of Mannan and had lived almost since the beginning of time. Along with her siblings, she served as a Rider of Mannan, doing the bidding of the Unseelie King. In the old days, she hunted giants and monsters with his siblings.
In September 2012, the King sent them after the Blackthorn family to retrieve the Black Volume of the Dead. Ethna went after Emma Carstairs and Julian Blackthorn in Cornwall, along with Delan, Airmed and Fal.
Alongside her siblings, Ethna fought Emma until Emma killed Fal with her sword Cortana. Ethna was devastated by Fal's death; she went ballistic and had to be held back by Delan. When Airmed called their steeds and they retreated, Ethna paused to glare at Emma in a way that promised revenge.
She later attacked the Blackthorns in London, using a human child to lure them out of the Institute. They almost succeeded in killing the Blackthorns until Annabel Blackthorn arrived and drove them away by threatening to reveal the Unseelie King's name.
Ethna is bloodthirsty, enjoying suffering in their opponents and showing no mercy. She very passionate about her loyalties and duties. She appears to care for her siblings very much and shows the most anguish when one of them is hurt. She is also cruel and not above using children to complete her missions.
Ethna is of slighter build than the other Riders. She has metallic bronze hair in a braid down her back and wears a bronze half mask, as well as a bronze cloak and bronze armor etched all over with designs of waves and the sea. Her longsword is sometimes slung over her back, seen over her shoulder.
- Longevity: As a Rider of Mannan, Ethna is very old and has been alive for thousands of years.
- Enhanced strength and speed: Ethna is able to move incredibly fast and deal heavy blows.
- Deceit: As a Rider of Mannan, Ethna is wild magic and could lie despite being a faerie.
- Lord of Shadows (first appearance)
Ethna is an Irish name which means "graceful".
- Ethna is the only female Rider.