Which emperor became paranoid after fighting wars with Decebalus?

The correct answer is Domitian. After his military engagements with Decebalus, the king of Dacia, Domitian became increasingly paranoid and wary of conspiracies against him. Domitian's reign was marked by a climate of fear and suspicion, particularly in the aftermath of his campaigns aimed at securing Roman borders and suppressing any potential threats from the Dacians.

Domitian's paranoia can be attributed to several factors, including the intense political atmosphere of his time and the significant losses Rome experienced in its confrontations with Dacia. His response was to implement strict measures to maintain control and eliminate perceived threats, which included a wave of executions and repressive policies against the aristocracy.

In contrast, Hadrian, Nerva, and Trajan had different focuses during their respective reigns. Hadrian is known for consolidating and fortifying the Empire's boundaries rather than engaging in expensive military campaigns; Nerva, who preceded Domitian, focused on reforms and stabilizing the Empire in a time of crisis; and Trajan, while involved in military conquests, had a reputation for a more balanced rule that didn't exhibit the same level of paranoia as seen in Domitian’s later years. Thus, it is the context of Domitian's rule and