Douglas Harper's Etymology Dictionary
souffre-douleur
1845, French, literally "suffer sorrow;" one who is in a subservient position and must listen to or share another's troubles, specifically "a woman who acts as a paid companion to an older woman."
Usage examples of "souffre-douleur".
The physiologists of the time of Moses --if there were vivisectors other than priests in those days--would probably have considered that other plague, of the frogs, as a fortunate opportunity for science, as this poor little beast has been the souffre-douleur of experimenters and schoolboys from time immemorial.