That group of kids everybody knew in high
school that individually were often the targets of derision and/or physical violence, but who through some
geek radar found one another to form an alliance, thereby lessening the probability that any one member is a victim.
The reference to the middle-age practice of isolating individuals with Hansen'
s Disease (Leprosy) and not allowing them to come into contact with any "normal"
people is apropos because if a "normal" (read non-geekified)
child were to associate with the leper colony, s/he is immediately labeled as suspect, and in extreme cases will be isolated him/her self, thus becoming a member of the colony.