Arianna (アリアンナ) is a heroine of Etrian Odyssey II Untold: The Knight of Fafnir. She is the daughter of the Duke of Caledonia and meets the protagonist since he and his friend Flavio are her escorts to perform a ceremony that takes place every 100 years in the ruins of Ginnungagap. She is of the Sovereign class which is the equivalent of the Princess and Prince class from Etrian Odyssey III: The Drowned City.
Her royal upbringing makes her somewhat oblivious to "normal" customs and terminology. Arianna often seems to appear dim at times, hence her calling herself "scatterbrained". She often tends to take things literally and not pay attention to details, being quite the naive and gullible character. She is always kind hearted and finds many things cute, even some of the monsters that lurk the labyrinth. Arianna is very helpful and optimistic, being the typical innocent princess.
Despite her normally gentle personality, she is quite conscious and even strict about manners. And when she is provoked too much to the breaking point, she will become so angry that anyone would be put down by her pressure. Simply put, Arianna is extremely scary when she's angry, so everyone avoids displeasing her.
Arianna was born into the Duchy of Caledonia and grew as a sheltered child and thus speaks very formally. From the moment she was born, she was given the title Daughter of the Mark as she was destined to undergo the centennial ritual in Ginnungagap. The legend called for her to travel to the Temple of Ginnungagap when she was 18 years of age. Her royal upbringing and status as the Daughter of the Mark heavily contributed to her being unable to make friends. But when she was a young girl, she went to study at the Midgard Library where she met the protagonist and Flavio and befriended them. She once told the Knight of Fafnir when they were young, "You are my first and only friend."
One day the trio was playing in the forest when a deadly beast suddenly attacked Arianna, knocking her unconscious. The Protagonist acted as a decoy to make way for his friends to escape. It was then when a power deep within him activated and he transformed into the Knight of Fafnir. He quickly killed the beast and transformed back, but blacked out and lost all memory of what happened and wiping out his memories of Arianna also. Flavio was the only witness of what had happened but no one of the Library believed his testimony intentionally to keep word of the power of Fafnir from going around. It was immediately after the incident that Arianna was sent back home to Caledonia with no memories of the Protagonist and vice versa.
- Arianna, despite being of equal status, has never been acquainted with Lady Gradriel in any way although they are both daughters of the Dukes of the respective neighboring Duchies of Caledonia and High Lagaard.
- According to Chloe, she eats with elegance, as one would expect from a princess. Furthermore, she's good at pointing out ingredients in dishes.
- The first time she shows her anger/angry sprite was when the protagonist chooses "That's that. Manners are manners," after Chloe transferred her onions of her "Bison Lamian" to Bertrand's dish.
- Arianna doesn't like spicy foods since she seemed to dislike dishes like " Gibier Curry Rice" and "Mala Inferno Pot".
- After making "Persimmon Pudding", Arianna mentions back at her home in Caledonia, there was a strange recipe for pudding. According to Regina, the recipe does exist and it was arranged that so the pudding can be made with much more ease. The steps for it are the following:
- Step 1: Mix flour with beef tallow.
- Step 2: Add eggs, sugar, some brandy, and dry fruits.
- Step 3: Mix them all together and boil.
- Step 4: When it's cooked, hang it in a well-ventilated place for a month.
- Step 5: Eat it!
- "Ummm.... Would that be because of me? Honored though I am to hear it, you and I don't have such a close relationship. I do of course see you as a friend, but..." (To the Fafnir Knight in an embarrassed state when she misunderstood his words)
- "But this view...! How can you speak of weather and temperature in the face of such vistas?" (To Bertrand about Petal Bridge Stratum)