Career
He has played right across the back line for Kerry. Early years: 2002 - 2005
In the final of that year he marked Diarmuid Marsden of Armagh. In 2003, Kerry reached the All-Ireland semi-final, but again suffered disappointment.
After a terribly below par performance against a Tyrone team who used what analyst Pat Spillane (himself of Kerry origin) called "puke football" to suffocate Kerry,
2004 was a busy year for Ó Sé.
First he lost the All Ireland Club Championship with his club He starred in the 2004 campaign showing great defensive awareness and beautiful on the ball skill.
In 2005, Ó Sé continued to perform for Kerry who this time were narrowly defeated by Tyrone. Many people from around the country felt the fact that Kerry had not been tested in the championship in almost a year and a half, and the fact that this was Tyrone"s 10th game of a gruelling campaign as key factors in the final result.
Again Ó Sé was overlooked in the All Star selection despite a sterling campaign.
Middle years: 2006 - 2009
Kerry bounced back in 2006. The team defeated Galway in the final of the National League again in a far less impressive game as the corresponding fixture 2 years earlier. Kerry were shocking in the Munster Championship, in which they were nearly defeated by minnows Waterford and eventually defeated in a replay against Cork.
However, this proved to be a false dawn for the rest of Ireland as Kerry regrouped.
They beat Longford in the qualifier and were written off for their quarter final against Armagh. Armagh and Tyrone were perceived as Kerry"s bogey teams in recent years and Armagh were expected to deal with Kerry in a similar fashion as Tyrone had done the previous year.
Marc was immense and scored 2 glorious points from the back, many experts said that there were few forwards in the game who could have taken their scores as well. Kerry gained revenge against Cork in the Semi-Final before handing Mayo and even more severe beating than they had two years earlier.
The team advanced to the All-Ireland series, and reached the final, in which they beat Billy Morgan"s Cork side 3-13 to 1-9.
lieutenant was Kerry"s 35th all-Ireland. In 2008, Ó Sé reached the National League and Munster finals with Kerry, but lost both. The team went on to reach their fifth consecutive All-Ireland final, but lost to Tyrone by four points.
Later years: 2010 - 2014.