Someone who takes the place of another (as when things get dangerous or difficult).

synonyms: backup, backup man, fill-in, relief, stand-in, substitute.

Dutch: vervanger

A person who reduces the intensity (e.g., of fears) and calms and pacifies:
— A reliever of anxiety.

synonyms: allayer, comforter.

A pitcher who does not start the game.

synonyms: fireman, relief pitcher.