'Demand' meant 'entrust completely' — from 'mandare' (put into the hand). It hardened into insistence.
An insistent and peremptory request, made as of right; the desire of consumers for a particular commodity or service; to ask authoritatively or brusquely; to require.
From Old French 'demander' (to ask, to request, to demand), from Latin 'dēmandāre' (to entrust fully, to give over to someone's charge), from 'dē-' (away, completely) + 'mandāre' (to order, to commit to one's charge, from 'manus,' hand + 'dare,' to give). The shift from 'entrust' to 'request forcefully' occurred in Old French. In English, the word intensified further: to demand is to place a claim in someone's hand
In French, 'demander' simply means 'to ask' — with no implication of forcefulness. Asking 'Puis-je vous demander quelque chose?' is perfectly polite. English borrowed the word but turned up the intensity: in English, to 'demand' is to ask with the force of authority or right. A French 'demande' is a question