reliever

nouns

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

"the star had a stand-in for dangerous scenes"; "we need extra employees for summer fill-ins"

backup, backup man, fill-in, relief, reliever, stand-in, substitute

is derived from

a person who reduces the intensity (e.g., of fears) and calms and pacifies

"a reliever of anxiety"; "an allayer of fears"

allayer, comforter, reliever

is derived from

a pitcher who does not start the game

fireman, relief pitcher, reliever

is derived from