(n.) One who sympathizes.

Maecenas abettor accessory accomplice acquaintance admirer advocate aficionado ally alter ego angel apologist approver backer best friend bosom friend brother buff casual acquaintance champion close acquaintance close friend collaborator condoner confidant confidante conspirator defender dependence encourager endorser exponent familiar fan favorer fellow fellow creature fellowman friend friend at court inseparable friend intimate lover mainstay maintainer neighbor other self paranymph partisan patron pickup promoter protagonist reliance repository second seconder sectary sider sponsor stalwart standby support supporter sustainer upholder votary well-wisher