Lame Duck Syndrome

A condition in which the affected individual is unwilling to exert effort into maintaining friendships so resorts to collecting 'lame ducks' (the socially inept) who are otherwise incapable of forming friendships. A degree of empathy is involved as those with lame Duck Syndrome lack the ability to leave people marginalised or uncomfortable in social situations; they gravitate towards the socially awkward 'lame ducks' in an attempt to make them feel more comfortable. The 'lame ducks' are consequently grateful and cling to the affected believing in the existence of a friendship, thus the affected often suffer as they do not end up socialising with the people they ought to be, but rather act as the glue holding together a group of social outcasts.
This syndrome may be recognised in an individual who does not appear socially defective, yet socialises (in an often perfunctory manner) with those who are; the 'weird kids', outsiders and the psychologically unstable.

Why is John hanging out with the weird kids again?
He's got Lame Duck Syndrome, he can't help it.