Siren is a cat-like Fairy of Songs and Mephisto's assistant. Born in Major Land, she was actually friends with Hummy until jealousy got the better of her—when Hummy snagged the annual "Melody of Happiness" title that Siren had held, she basically threw a fit and demanded to become Mephisto's right hand instead. As Siren, she's seriously powerful: she can spawn Negatones using dark magic and transform into anyone she wants thanks to her enchanted necklace. In her human form, Ellen, she's a skilled fighter who can conjure musical notes to throw as weapons.
Things changed in Episode 21 when her protective instincts kicked in. Watching Hummy get captured by the Minor Trio awakened her Pretty Cure potential, which shattered her necklace and locked her into human form permanently. Stripped of her transformation powers, she ended up crashing with the Shirabe family and started attending school alongside Hibiki and Kanade. She's actually pretty notable in the Pretty Cure series as one of the few characters to flip from villain and mascot role to becoming a Cure herself.
As Cure Beat, her dark purple hair shifts to bright purple with a side ponytail, and her theme color is blue. Her Fairy Tone is Lary, and she fights with the Love Guitar Rod, which channels another Fairy Tone called Sory. Her transformation call: "Playing the soulful tune, Cure Beat!"
Content compiled by AnimeList.moe from publicly available sources.
