Aletheia is kind towards the McDuck family who arrives at Mervana the first time. However, when it comes to Scrooge McDuck's negative attitude, she tells him to change it from negative to positive to find honesty.
Role in the series
Aletheia was introduced in the Season 3 episode, "The Lost Harp of Mervana!".
As the McDuck family, with the exception of Della arrives, Aletheia and Vero happily greet the McDucks arriving at Mervana where she tells Webby that all the inhabitants of Mervana are free from stress. The McDucks follow along with Aletheia where in Mervana, the inhabitants always believe in truth to which Vero tells the McDucks that they just find the truth themselves. Aletheia tells them with one spell, it can allow all the inhabitants to live in peace and harmony under the sea just as the McDucks arrive at Mervana. Arriving their, Aletheia tells a prophecy to the McDucks that many years ago, the city's ancestors spent their lives between land and sea until their leader King Honestus brought trouble to the inhabitants to escape the land to which according to her, Honestus seemed his own truth and never returned, hoping that he can return in Mervana sometimes. After telling the prophecy about the king, Vero brings in a drum ceremony for the McDucks in finding honesty. During arts and crafts time, Scrooge does his own fish tail design linked to the harp of Mervana to which she tells him that this design is not about honesty and truth but rather linked to negativity, much to Scrooge's frustration.
Aletheia and Vero look at Donald's fish tail to which the two are overjoyed of his tail. Later, Vero tells all the McDucks that they all have truthful relationships in Mervana except for Scrooge to which according to Aletheia, Scrooge has a bad reputation of negative and judgmental attitude stopping his honesty. Scrooge demands Aletheia to find the harp during the conversation to which she denies, warning Scrooge that he will not find the knowledge he seeks until he achieves his truth, forcing Scrooge to go back to the arts and crafts section.
Back at the arts and crafts section, Aletheia tells Huey and Dewey that their inner light shines bright amongst their truth while preparing for the sacrifice of their worries. Preparing for the sacrifice, Scrooge accepts Aletheia and Vero's offer about giving up his negative attitude to which he accepts, accepting Scrooge's agreement. Later after Louie, Webby, and Mrs. Beakley escape with the magic harp, Louie warns the inhabitants to escape from the sea monster lurking in a hidden chamber to which Aletheia denies. Just as the sea monster terrorizes Mervana, Aletheia tells Webby that Honestus betrayed them to which Webby tells her and Vero to face the real truth of everything terrible. Louie, however, tells the real truth to the two that Mervana's king turned into a monster, telling them to believe their place inside their heart to which the two agree.
Aletheia, Vero, and the other citizens of Mervana fight against a corrupted King Honestus while she, the McDucks (this time with Della joining in), and the rest of the Mervanans escape from the ancient tower where Louie, Webby, and Mrs. Beakley found the magic harp. Aletheia, Vero, and the rest of the Mervanans, lose their tails and have their feet revealed, alongside King Honestus who reverts to his normal form just as the Harp warns him to rebuild his kingdom with hard work as punishment just as Aletheia, Vero, and the rest of the Mervanans plan to conquer their fear of land and adapt to a new life from sea and land to rebuild the fallen kingdom by working together to rebuild it just as the McDucks leave Mervana.
- Aletheia is named after truth and philosophy.