The character(s) have no friends, and quickly build friendships with the rest of the (also friendless) cast. However, they aren't loners, weren't ostracized by their peers, or grew up away from other kids. They simply didn't have, or allude to having had, friends prior to the start of the story. This is a stock, implicit but rarely stated background to many characters. Much like Forgotten Fallen Friend, they never mention old friends or being in activities/groups with others. This is often justified by having the characters move around a lot, or go from home to someplace completely new. It does however facilitate them wanting to make new friends and get the plot rolling. Oddly, this "zero to popular" burst is often followed by getting stuck in a Limited Social Circle. Of course, The Power of Friendship is strong with them, and a Sixth Ranger or enemy might join later. Occasionally this background is explored with the introduction of a Beleaguered Childhood Friend later, or the old childhood sweetheart.
Hello, Unknown Troper. You'll need to get known to lend a hand here.