“I can't just sit around hoping someone else figures out what happened!” ― Undine
The following sections contain unmarked spoilers. Read at your own risk!
While shy, Undine was often the mediator of Team Alchemical. She tends to lack confidence in herself and often feels guilty for things that were out of her control.
Undine feels deeply guilty over the deaths of her teammates. She believes that it's her fault her teammates died that night, as The Purple One, who seems to specifically target her, controlled the monster that killed her friends. Undine greatly fears being a burden to others, unable to do anything to save the people she cares about.
Two years before the story begins, Undine had the dream and became the first of Team Alchemical to gain her magical girl powers. As a group, they became one of the most popular magical teams in The City.
One night, approximately two years after Undine received her powers, Team Alchemical went on patrol without Alchemical Aether, its most powerful member, and Alchemical Fire, Alchemical Air, and Alchemical Earth were killed by a powerful monster. Undine was only able to survive by controlling the flow of her blood. Alchemical Aether soon arrived on the scene, and rushed to heal Undine; in doing so, she lost her powers, leaving Undine the sole remaining active member of Team Alchemical.
After the deaths of her teammates, Undine has been constantly tormented by a mysterious purple being known only as The Purple One. This being seems to have controlled the monster that killed Gwen, Sylvia, and Sally. In her second appearance, The Purple One appeared to Undine and spoke to her, revealing that Undine forgot something important about the night of her teammates' deaths. The Purple One often uses Undine's insecurities to taunt and distract her.
Soon after the death of her team, Undine became friends with Heartful Punch, an extremely popular magical girl who fights solo. They begin fighting together every night, and Undine becomes a member of HP’s Magical Girl Power Training Club. One night, HP proposes that the two form an unofficial team, and Undine accepts.
The night after, Undine and HP fight a huge monster, possibly controlled by The Purple One, that breaches the Inner Barrier and attacks a family. When Undine is fighting the monster, she is attacked by it and trapped. HP attempts to save her, only to be caught and slowly lowered into the monster’s jaws. At a loss at what to do, Undine’s inner fears come back to torment her, until she regains control and kills the monster with an extremely powerful water jet.
Since she was healed by Alchemical Aether, Undine’s power level seems to have increased, as shown in Chapter 8 when she destroyed the monster with her water jet. As shown in Chapter 9, before she was healed by Tessa, Undine had trouble directing enough force behind the jet to do any damage.
Undine is a short, black teenage girl with curly hair. Her hair was originally a dark blue-black color, but became bright blue after receiving her powers, and forms into short drill curls when transformed. She has blue eyes, which were originally brown before she received her powers. After being saved by Tessa, her eyes changed such that her irises remained blue while her pupils became colored pink when transformed, and appear to glow during extreme uses of her powers. Her clothing choices seem to lean towards shades of dark blue, and she usually wears skirts when not transformed.
Undine’s magical girl outfit is a short dress with a puffy skirt similar to the rest of Team Alchemical. Undine's dress is different shades of blue and white with yellow accents. The top is mostly bright blue, is sleeveless, and has a collar with yellow trim and a dark blue bow around the neck. It also has a large white stripe down the middle. Her skirt has two layers. The peplum, its top layer, is bright blue with yellow curlicue accents, trimmed with lighter blue curlicues that slightly resemble sea foam. A dark blue, semicircular layer of fabric with a yellow stripe separates the peplum from her white underskirt. The bottom layer of her skirt is white with a yellow stripe at the bottom and is trimmed with blue lace that is the same color as her hair. Her accessories include another dark blue bow and headband in her hair, white evening gloves, a blue belt with her alchemical symbol on it, and bright blue rainboots with yellow curlicue accents.
Since she was healed by Tessa, Undine's costume has gained a giant dark blue ribbon on her back, similar to Tessa's, while losing the loops of fabric that hung off her shoulders. Her long white socks became stockings, and the design of her peplum was slightly changed as well. The design of her boots changed to look more like rainboots and her hair bow gained ribbons. Many of these changes have changed her costume design to look more unique compared to her former teammates. The Chapter 8 interstitial and Chapter 9 flashback show that these changes are canonical and not simply due to different artists.
Undine has the ability to manipulate water. She is stronger on days with higher ambient precipitation, such as rain or fog. She can extend her senses through fog and mist, detecting friends and foes from afar, and travel quickly via 'surfing' on a plane of water if it is raining hard enough. Similarly, if there is sufficient environmental water, she can ride it to rise at least a couple of stories in altitude. The amount of water she can produce without environmental assistance is limited. On at least one occasion, she has manipulated a substance composed mostly of water with incomplete success, keeping herself from bleeding out. The strength of her manipulation is affected by her emotional state and possibly by the transfer of power performed by Tessa Quinn. Under extreme duress, she was able to weaponize water much more effectively than she could during unchallenged practice.
- Undine's name is pronounced un-deen.
- Like all members of Team Alchemical, Undine Well's name is a reference to her element. Undines are elemental spirits associated with water, and wells are a source of water.
- A very early version of Undine can be seen in March 2011 on Mary's Tumblr. There's no name given, but it is a blue, water-themed magical girl with the alchemical symbol for water on her chest.
- While Sally is the only in universe character to call her Undies, Mary has used the name in Alt-Text and apparently when scripting.
- Mary Cagle has said Undine's Hogwarts House would be Hufflepuff.