barmecide n., an insincere benefactor; one who holds out illusory offers, or who promised , but does not deliver.
the original Barmecide is to be found in one of the tales of the arabian nights, and his name has become synonymous with deceit, illusion, hypocricy, and at the proffering of bounty, only to with hold the bounty until the proffer's terms are met.

who knew there was this wonderful word to define so foul a character? I mean, i usually use the analogy of the school yard bully, who happens to own a baseball, and hold the whole team hostage to playing by his rules, or he takes away his ball..
we have all come across such characters, the kind who spoil things for everyone, unless they have everything their own way, and who offerings of help and kindness, are so insincere as to be transparent.

well, in the Arabian nights, he got his come uppance! the Caliph had him and his family imprisoned and exectuted them.