well, i wasn't speaking on slavery in the historic context, because of course they had each others back. harriet tubman, anyone?
but as far as the movie, which is a fictional historical drama, i think that is how django felt. he was alone it the world worth nothing more then what someone was willing to pay (which in history i'm sure slaves may have felt). the one person he loved more in the world and who loved him back was taken away. he didnt care about any of those other slaves.