Aortoesophageal fistula (AEF) is a rare and life-threatening condition that can result from foreign body ingestion, particularly in vulnerable populations with impaired communication, where diagnosis may be delayed. A 26-year-old male with severe autism and limited expressive capacity presented to the emergency department with a two-day history of fever and melena. Two hours prior to arrival, hematemesis occurred while attempting oral intake. Caregivers noted behavioral changes and deterioration in general condition over the preceding approximately 10 days. Diagnostic imaging revealed a large, curved metallic foreign body that had perforated the esophageal wall, traversed the prevertebral space, and appeared to penetrate the thoracic aorta with its tip, leading to mediastinitis and AEF. Despite emergency surgery with cardiopulmonary bypass, the patient succumbed to sepsis and multi-organ failure within 24 hours postoperatively. This case highlights the importance of clinicians considering the potential for an asymptomatic period following sharp metallic foreign body ingestion, which can lead to severe complications, particularly in patients with communication impairments. The asymptomatic interval can result in significant complications, including luminal erosion, rupture, or the development of a fistula with adjacent structures. Emergency physicians must suspect AEF, especially in patients with foreign body ingestion, when gastrointestinal bleeding is accompanied by signs of severe infection. Timely use of CT imaging is critical for confirming the diagnosis and determining the need for emergency surgical intervention. This case underscores the necessity of thorough evaluation in managing potentially life-threatening foreign body ingestion.