Someone defects to the opposition because he was rejected by his own kind. Is this simply a rejected lover getting revenge?
Sorry I’m not too sure what you are asking here. It seems a bit vague. Genearlly though if a person is “rejected” from one group s/he will no longer identify with that group and seek a new one. If that new one accepts him/her, it is often not an act of revenge against the old group, but an act of loyalty to the new one. Really though without specifics I can’t tell you.