Final answer:
The emperor in question is likely Macrinus, who ruled for less than a year during the Crisis of the Third Century and was one of the few emperors to die of natural causes.
Step-by-step explanation:
The student's question seems to point towards the turbulent times known as the Crisis of the Third Century, particularly focusing on an emperor who ruled for less than a year and was the only one among many to die of natural causes.
According to the provided reference, the only emperor who fits this description is likely Macrinus, who ruled for less than a year after the assassination of Emperor Caracalla in 217 CE. Macrinus was part of the rapid succession and instability during the Crisis of the Third Century before he met his demise.
This period was characterized by frequent changes of emperors, with many being assassinated or dying in battle. It was a stark departure from earlier times in the Roman Empire, such as the stable and prosperous rule of emperors like Augustus.