Boston, MA 031710 After siblings Brendan (cq) ,20 month-old, and Nora (cq), 4, Dowling of West Roxbury attended the St Patrick's Day mass at the Cathedral of the Holy Cross on March 17, 2010 they examine the shamrock plants their parents picked up for them at the service. (Essdras M Suarez/ Globe Staff) BEHIND THE SCENES Despite having been in Boston for over eight years now, this is one event I had never covered so I didn't really know what to expect. At the end of the homily I recalled being somewhat concerned since I didn't have any good pictures yet. I usually stick to the rule of not photographing children unless they are doing something extraordinary (they are just too easy and a lot of photographers take the easy way out during an assigment by focusing on children. But once I saw the Dowling siblings decked out in their Irish garb, I knew this was a rule breaker of a situation. The boy and girl examining their shamrocks happened after their parents had sat them down for a photo. The little boy offering his shamrock to archbishop Sean O'Malley happened luckily while I was on my knees getting ready to photograph the clergy man. This one was preparation, anticipation and a huge dose of serendipity all wrapped up in one.