Colin was a year behind the Golden Trio at Hogwarts, and was a source of constant annoyance to Harry during his second year (Colin’s first) because he was always following Harry around with his camera, wanting to take pictures of Harry to send home to his dad (mostly, I think, to show his dad how wizarding photos worked, but also to show his dad that Harry was his friend). Colin eventually grew out of the hero worship (I think he did, anyway) but remained loyal to Harry until his death at the Battle of Hogwarts. He was an enthusiastic student of Harry’s in the D.A. during Harry’s fifth year, when Dolores Umbridge (aka “Toad Face”) was the so-called professor of Defense Against the Dark Arts (although even a toddler could tell you she was rubbish at it). He and his brother Dennis were killed during the Battle of Hogwarts when they both snuck back into the castle to help with the fighting. Harry saw Neville and Oliver Wood carrying his body into the Great Hall during the temporary cease-fire granted by Voldemort so that the fighters could collect their dead (nice of the old snake, wasn’t it?). Seeing someone so young killed needlessly only strengthened Harry’s resolve to stop Voldemort once and for all.