Miles O'Brien was born in Dublin in Ireland on Earth in September 2328. Besides his mother and father Miles has 2 brothers. He show great pride in his family history and can trace his family tree back to a mediaeval King called "King Brian Boru and further on in time to Sean Aloysius O'Brien, a marta who was killed in 1902 during a strike in Pennsylvania.

Unlike most young people O'Brien enlisted in Starfleet as an NCO or None Commissioned Officer. Which meant he wouldn't be trained as an officer but he'd be in Starfleet for many years gaining valuable experience working his way up the ladder through pure hard work.

As a crewmen O'Briens first big posting was on board the USS Rutledge NCC 57295, commanded by Captain Benjamin Maxwell.

When the Federation went to war with the Cardassian Union a number of events would have a significant effect on the young mans life. One of these was a Cardassian attack on Setlik III in 2347. The Cardassians believed the Setlik III outpost was a staging point for an invasion into their space. When the Rutledge responded to the outposts distress signal O'Brien had to repair a field transporter in order to save himself and 13 other Starfleet personnel.

Before escaping O'Brien witnessed the attack and the brutality of the Cardassian Militia placed a deep mistrust and hatred towards Cardassians. Which looks like lasting his entire life.

Miles was later promoted to the Rutledges tactical officer. With this new role came a wealth knowledge about engineering and ship systems.

When the war ended Miles came to terms with the horrors of Setlik III.

After 17 years aboard the Rutledge Miles transferred to the Federations new Flagship in 2364, the USS Enterprise NCC 1701-D. Commanded by Captain Jean Luc Picard.

At first he's a member of the bridge crew as conn officer (Which basically means he's the ships pilot.) Soon after though he earns a promotion to Transporter Chief, a role he maintains for the rest of his service aboard the Enterprise.

His hobbies include Kayaking on the holodeck and caring for his pet tarantula.

One of, if not the most momentous encounter he has aboard the Enterprise is when Lt Commander Data introduces him to Keiko Ishukawa. After a number of dates they began a relationship. And in 2367 they are married by Captain Picard on the Enterprise. As Data introduced the two they ask him to serve as "Father of the bride" and give Keiko away.

A year into their marriage they have a daughter, and call her Molly. She is born in Ten Forward, delivered by Lt Worf.

The Enterprise encounters a number of quantum filaments. Which render the ship practically powerless. The in charge bridge officer is killed leaving Troi in charge. Having hardly any command experience Troi looks to the other bridge crew on duty for support. O'Brien in on the bridge at the time conducting a transporter simulation.

Also in 2367 O'Brien plays a key role in tracking down his former Commanded Captain Maxwell, who's been attacking Cardassian ships and outpost. Maxwell believes the Cardassians are preparing a new assault on the Federation. Having served under Maxwell during the Federation / Cardassian war Miles feels uncomfortable at stopping his former Captain, but still carries out his duty to Captain Picard.

O'Briens service on the Enterprise ends in 2369 when he transfers to the Federations new outpost in the Bajoran Sector on Deep Space Nine. With the transfer comes a promotion to Chief of operations (Basically the equivalent of a starships Chief Engineer). Proving how valuable a member of crew he is, Captain Picard personally transports O'Brien to DS9 from his favourite transporter room, No.3.

The O'Brien family leave the Enterprise with mixed emotions, and this causes a lot of friction in their relationship during their early time on DS9.

During his many years in Starfleet Miles has made countless friendships. His closest friend strangely enough is Dr Julian Bashir. When they first met on DS9 the Chief found Bashir annoying and went out of his way to avoid him. Eventually the 2 men become the closest of friends.

In 2371 Keiko accepts a job on Bajor. Both her and Molly leave the station for months at a time. Although he misses his wife and daughter Miles wants her to maintain her career. Its at this point that Bashir and O'Briens friendship grows.

They play darts in Quarks and enjoy recreating historic battles in the holosuites.

When Keiko gets pregnant again she's involved in a shuttle accident which forces Bashir to transport the unborn child into Major Kira's womb or Keiko and the baby will die. Due to the process not being reversible Kira has to carry the baby full term. To help care for the now pregnant Kira and be closer to their child Kira moves into the O'Briens quarters. Kira and Miles become close and there's even a hint of romance.

When the child is born in 2373 they call him Kirayoshi.

Nearing the end of the Dominion war O'Brien hesitates in telling Bashir that he's leaving DS9 to teach at Starfleet Academy. Showing just how close the 2 men have become during the years they've spent on DS9.