seconder (n.)

• abettor
• admirer
• advocate
• aficionado
• angel
• apologist
• backer
• buff
• champion
• defender
• dependence
• endorser
• exponent
• fan
• lover
• mainstay
• maintainer
• partisan
• patron
• promoter
• protagonist
• reliance
• second
• sectary
• sider
• sponsor
• stalwart
• standby
• support
• supporter
• sustainer
• sympathizer
• upholder
• votary
• well-wisher