Iduna from Disney's Frozen is often typed as ISFJ or INFJ in modern MBTI discussions. When examined through the framework of Carl Jung's Chapter X of Psychological Types rather than modern MBTI stereotypes, ISFJ emerges as the most convincing four-letter equivalent. Although Jung did not use the MBTI system and Iduna is a fictional character, her personality can be interpreted through Jung's cognitive functions as they are described in Chapter X. This analysis is therefore an interpretation of her consistent behavior in Frozen and Frozen II rather than a definitive psychological classification. The dominant function associated with the modern ISFJ type is Introverted Sensing (Si). Jung described the introverted sensation type as one whose perception is shaped by subjective impressions and deeply rooted experiences. Rather than constantly seeking novelty, such individuals are guided by memories, personal responsibility, and the preservation of what they value. Iduna consistently demonstrates these characteristics. Having grown up in the Enchanted Forest and witnessed the conflict between the Northuldra and Arendellians, she carries these experiences throughout her life. Instead of forgetting the past, she quietly preserves its lessons and allows them to guide every major decision she makes. Her actions are consistently rooted in memory, tradition, and the desire to protect future generations from repeating earlier mistakes. Jung emphasized that introverted sensation does not merely recall events but gives them profound subjective significance. Iduna embodies this orientation by carefully safeguarding knowledge about Elsa's powers and her own Northuldra heritage. She does not reveal everything immediately because she believes that certain truths should be understood only when the proper time arrives. Rather than reacting impulsively to changing circumstances, she draws upon past experience to determine the safest and most responsible course of action. This reliance on accumulated wisdom strongly reflects Jung's description of dominant Introverted Sensing. The auxiliary function of ISFJ is Extraverted Feeling (Fe). Jung described the extraverted feeling type as someone who naturally adapts to the emotional needs of others and seeks interpersonal harmony. Although Iduna is reserved, her life consistently revolves around maintaining peace within her family and protecting those she loves. Nearly every important decision she makes is motivated by concern for Elsa, Anna, and King Agnarr. After Elsa accidentally injures Anna, Iduna immediately focuses on comforting both daughters rather than assigning blame. She carefully balances Elsa's fear with Anna's innocence, attempting to preserve emotional stability within the family despite overwhelming circumstances. Jung noted that healthy Extraverted Feeling often expresses itself through gentle encouragement rather than dramatic emotional displays. Iduna perfectly reflects this pattern. She remains calm during moments of crisis, offering reassurance instead of panic. Her famous lullaby, "All Is Found," serves not only as comfort but also as emotional guidance. Through stories, affection, and quiet wisdom, she creates an atmosphere of security that allows her children to endure fear without losing hope. Her emotional expression is consistently directed toward supporting others rather than seeking attention for herself. The tertiary function of ISFJ is Introverted Thinking (Ti). Jung described introverted thinking as constructing internally consistent explanations of reality. Although this function is not dominant in Iduna, it appears in her careful understanding of Elsa's abilities. She does not simply fear the magic or dismiss it as a curse. Instead, she patiently seeks explanations, consults the trolls, and gradually develops a coherent understanding of what must be done to protect Elsa. Her reasoning remains quiet and reflective rather than argumentative, supporting her practical decisions without overshadowing her emotional priorities. The inferior function of ISFJ is Extraverted Intuition (Ne). Jung regarded the inferior function as the least conscious aspect of personality, often emerging during periods of uncertainty or personal growth. Iduna generally prefers stability and familiarity, but she demonstrates developing intuition when she realizes that Elsa's powers may have a greater purpose beyond immediate control. Rather than remaining confined by tradition, she eventually decides to search for the truth about the enchanted forest despite the considerable risks involved. This willingness to explore unknown possibilities illustrates the influence of inferior Extraverted Intuition. While it never becomes her primary mode of operation, it enables her to move beyond the safety of familiar routines when her family's future requires it. Jung observed that introverted sensation types frequently appear calm, dependable, and quietly devoted because their psychological energy is directed inward toward preserving meaningful experiences. Iduna consistently embodies these qualities. She rarely seeks recognition or authority despite holding the position of queen. Instead, she supports her husband, nurtures her daughters, and accepts personal sacrifice as a natural responsibility. Her influence is subtle but profound, shaping Elsa's and Anna's development long after her death through the values and memories she leaves behind. Some viewers identify Iduna as an INFJ because of her mysterious knowledge and intuitive understanding of Elsa's destiny. While she certainly possesses foresight and wisdom, Jung distinguished intuition from experience-based perception. Iduna's decisions consistently originate from remembered knowledge, established traditions, and lived experience rather than symbolic visions or unconscious insights. Her guidance reflects accumulated wisdom more than abstract intuition. Even her understanding of the enchanted forest is rooted in firsthand experience rather than speculative interpretation, making dominant Introverted Sensing a stronger explanation than dominant Introverted Intuition. Others argue that she is an ESFJ because of her nurturing personality and devotion to family. However, Jung distinguished outward warmth from psychological orientation. Iduna's emotional life remains deeply private and reflective. She is neither socially expressive nor energized by constant interaction. Instead, she quietly fulfills her responsibilities while relying upon personal memory and careful observation. Her reserved demeanor and reflective decision-making indicate an introverted foundation rather than an extraverted one. Viewed through the framework of Chapter X of Psychological Types, Iduna most plausibly corresponds to the modern MBTI type ISFJ. Her lifelong reliance on memory, experience, and personal responsibility reflects dominant Introverted Sensing, while her nurturing concern for family demonstrates auxiliary Extraverted Feeling. Her thoughtful analysis supports tertiary Introverted Thinking, and her willingness to embrace uncertain possibilities during crucial moments aligns with inferior Extraverted Intuition. Although fictional characters cannot be typed with complete certainty, the ISFJ interpretation provides the most coherent explanation of Iduna's motivations, behavior, and enduring influence according to Carl Jung's original theory presented in Chapter X of Psychological Types.