Final answer:
Vahan's greatest fear upon reaching Constantinople would likely involve the prospect of the city's destruction, the violence that followed Mehmed II's conquest, and the personal risk of being captured or killed.
Step-by-step explanation:
Vahan's greatest fear once he reaches Constantinople would likely be the destruction and collapse of the city under the siege by Mehmed II's forces, the brutality and chaos following the conquest, and the personal peril of being captured or killed during the conflict. The historical context shows that the conquest of Constantinople by the Ottomans under Mehmed II, also known as Mehmed the Conqueror, in 1453 marked the end of the Byzantine Empire and led to widespread fear and trepidation amongst the inhabitants and defenders of the city. The capture of Constantinople included acts of violence and the taking of captives, as recounted by survivors like Konstantin Mihailović in his Memoirs of a Janissary, highlighting the perils of living in a city under siege and the subsequent worries of its people about their fate.