Miles O'Brien (mirror)

In the primary mirror universe, Miles Edward "Smiley" O'Brien was a Terran slave of the Klingon-Cardassian Alliance with a theta designation until 2370. With the death of Captain Benjamin Sisko a year later, he became the leader of the Terran Rebellion. When Sisko first met O'Brien, O'Brien's serious demeanor was so noticeable that Sisko decided to designate O'Brien as "Smiley", a name that stuck thereafter.