ally
verb
°To unite, or form a connection between, as between families by marriage, or between princes and states by treaty, league, or confederacy.
°To connect or form a relation between by similitude, resemblance, friendship, or love.
noun
°One united to another by treaty or league; — usually applied to sovereigns or states; a confederate.
°Anything associated with another as a helper; an auxiliary.
"Science, instead of being the enemy of religion, becomes its ally. --Buckle."
synonyms: make common cause