sympathizer

noun

1. (derogatory, often)A person who sympathizes (with a political cause, a side in a conflict, etc.); a supporter.

   “His reputation was ruined when it was revealed that he had been a Nazi sympathizer before the war.”

   “[…] she exposed herself to the fury of the sympathizers with slavery, without fear, and suffered their blows without flinching.”

   “‘[…] And I tell you that the slightest suspicion of my loyalty could be ruin for me, ruin! If it were ever breathed that I were even a sympathiser with this rebellion, there iss an end of me.’”

   “The Ardent Spirit pupils now belong to him alone and through them he’ll set his plans in motion, moulding them to be warrior saints, brilliant in deceit against the West and its sympathisers here at home.”

2. (archaic)A person who has, shows or expresses sympathy (with another person or people); a person who enters into the feelings of another.

   “[…] it is a sad case when the truly godly, who are cordial sympathizers, and earnest intercessours in the straits of a Nation, are stricken dumb in a day of calamity […]”

   “[…] I am a sympathizer in every part of thy distress, except (and yet it is cruel to say it) in That which arises from thy guilt.”

   “Not a mood of his but what found a ready sympathiser in Margaret; not a wish of his that she did not strive to forecast, and to fulfil.”