Star Trek: 10 Things You Didn't Know About Miles O'Brien

Bashir and O'Brien's friendship became a cornerstone of Deep Space Nine. Though the seeds were planted in early episodes like The Storyteller and Armageddon Game, it was Explorers that saw the biggest scene for them both - at least in terms of the writing team. Colm Meaney and Alexander Siddig suggested the song Jerusalem for a drunken sing-along (after other suggestions were deemed ineligible for the cost of rights).

Once the writers saw this, more and more scripts began to feature both men spending time together. Think of all of those holodeck scenes, as well as that confession in Extreme Measures, where Bashir openly admits to loving Ezri - but liking Miles even more. 

Siddig felt that their friendship was the truest, the most real even, in all of Star Trek, an idea shared by Ira Steven Behr. The obvious comparison is Kirk and Spock, though that relationship was boundered by rank and duty. In fact, Bashir only pulled rank on O'Brien once, in Hippocratic Oath, as their friendship was often entirely separate from their duties. They helped each other develop as characters. O'Brien may have begun the series a little rough around the edges, while Bashir started as the naive sex pest of the Promenade. 

Together, they balanced each other, helping both characters become real, rounded men.