What would Sean do? Loved ones mourn: Pallbearers carry the casket of fallen police officer Sean Collier. When he was 6 years old, Sean Collier was sitting in a booth at a Papa Gino's with his mother, Kelley, and his little brother Andy, having a pizza. There was a woman in another booth, alone, and she was crying. ""Mum,"" Sean Collier whispered, leaning across the table, ""you've got to go talk to that lady."" Loyal brother, doting uncle and dutiful son: Sean Collier. Kelley looked over at the woman and tried to reassure her son. ""Sean,"" she said, ""I'm sure she just wants to be alone."" ""Maybe she has no one,"" Sean replied. ""You're a nurse, mum. Please go talk to her."" Her conscience nudged by a 6-year-old boy, Kelley walked over to the woman and asked if she was OK. On Monday morning, as they prepared to bury their brother, the siblings of Sean Collier, the MIT police officer murdered by inexplicable hatred, asked me to listen to what they call Sean stories. They knew that people all over the world knew Sean was a dedicated, compassionate police officer. But they wanted people to know about the 27-year-old who was a loyal brother, a dutiful son, a doting uncle. They wanted people to know that in a sprawling family that grew up in a sprawling house in Wilmington, the second youngest of six kids was their moral compass. That the internal question asked so often by Joe Collier, his wife, and their kids was, ""What would Sean do?"" When he was a little boy, from the age of 3 or 4, Sean was obsessed with the American flag. He drew it constantly. With crayons. With pencils. With magic markers. And then he'd hand them out to family, friends, and total strangers. From a tender age, he was an entrepreneur. He would gather rocks, paint them vibrant colors, then set them out a table on Lorin Drive and try to sell them. ""Sean,"" his brothers and sisters told him, ""no one is going to buy a painted rock."" But he was irrepressible, and some people in the neighborhood couldn't resist the earnest young Collier kid. They bought his rocks. His sister Jenn Rogers and he were close in age, and they were inseparable as kids. They sat together on the big recliner in the living room, brother and sister, and they'd build forts with blankets draped across furniture. Andy Collier looked up to his big brother Sean. Once, when Andy went to step on an ant in their kitchen, Sean stopped him. ""You can't kill it,"" 7-year-old Sean Collier told his brother. ""It's a living thing. Pick it up with a napkin and put it outside."" Jennifer Lemmerman was always close to her brother Sean but they really bonded one summer, when Sean was in high school and Lemmerman was in college. They shared a summer job at a medical office in which they had to transfer a series of medical records into a computer system. To pass the time, they listened to the radio, and at one point the station ran a fund-raiser for the Jimmy Fund. Sean was transfixed by the stories of little kids getting cancer and getting better. ""Sean was so profoundly affected by those stories,"" his sister said. ""He went home that night and made a donation. He was in high school. He didn't have any money, but he set up an automatic withdrawal from his bank account. He had that automatic withdrawal until the day he died."" His big brother Rob Rogers was in awe when Sean helped a family that lives down the street. The father had a stroke. The son got in an accident and lost his leg. ""He was in the police academy, paying his own way, but somehow Sean scraped together $1,000 for that family,"" Rob Rogers said. ""I still don't know how he did it."" Sean's sister, Nicole Lynch, was the oldest and the first of the siblings to have children. When her oldest, 5-year-old Kailey, complained about getting glasses, saying it would make her look awkward, Uncle Sean came over for a visit. ""You look beautiful in those glasses,"" he told his niece. ""They make you look smart."" Kailey smiled, and her uncle handed her a case that he had used when he wore glasses as a child. Kailey treasures the case and still keeps her glasses in it. At MIT, Sean Collier looked after the students with the same paternal concern he had for his nieces. If some people dismissed some of the MIT kids as nerds, Sean was fiercely protective of them. When a young woman was assaulted on campus and was terrified at the prospect of identifying her attacker, Sean showed up and literally held her hand. ""When people say he was born to be a cop, they should know that didn't start when he was 18,"" Rob Rogers said. ""It started at 3, when he began looking out for everybody."" Sean Collier grew to love country and western music. One of the country music stations plays the national anthem at noon every day, and whenever Sean was in his cruiser at noon, he would turn on that station and listen to the national anthem. The love of flag he developed as a little boy never left him. And yet he was especially welcoming to the MIT students who came from countries where the police are not trusted. He won them over with his easy smile, a kind word, his remarkable ability to remember even the most unpronounceable names from far-flung lands. His brothers and sisters sat there Monday, preparing to say goodbye a final time, and they smiled and laughed more than they cried because Sean Collier did so much in 27 years, and one thing he did was teach his siblings how to live a good life. ""I am so proud to be his brother,"" Rob Rogers said. ""He made me want to change the way I live. He made me want to be better to people, to protect people. He made me want to be like him.""