From Michel de Certeau’s The Possession at Loudun (pg.43-44):
Fragile, unstable, contested, the words ascribed to the diabolical transcendence flew out of sight. They were compensated for by increased exhibitionism. Soon they were to be replaced by the themes of preaching: the preaching devils would represent the last of diabolical discourse, but a discourse nonetheless useful. Already, with the secondary and facetious malice to which Jeanne des Anges alluded in her autobiography, the possessed women themselves would deny the exorcists those proper words that they expected:
When asked: Quis es tu, mendax, pater mendacii? Quod est nomen tuum [Who are you, liar, father of lies? What is your name?] the demon said, after a long silence: “I forgot my name. I can’t find it … ”
And commanded once more to say his name, he said: “I lost my name in the wash.”
The intervention of royal justice will strike a blow against this linguistic esoterism from which it will not recover. The devil will be either the witnesses or the accused, and they will speak French like everybody else.
I wish I had the French edition to check but I’m assuming – because the text always indicates and translates Latin – that the final reply is in French and captures the frustrated breakdown of the possessed’s pretense to Latin.