1) Admirer 2) Booster 3) Champion 4) Friend 5) Maintainer 6) Protagonist 7) Supporter 8) Sustainer 1) Maintainer 2) Sustainer 
• (n.) A broker or auctioneer; a tradesman. • (n.) One who, or that which, upholds; a supporter; a defender; a sustainer. • (n.) An upholsterer. • (n.) An undertaker, or provider for funerals.
HMS Upholder was a British U Class submarine of 540 tons displacement launched and sunk during the Second World War. HMS Upholder was powered by two Davey Paxman diesel engines providing a top speed of 11 knots surfaced and two electric motors providing a top speed of 9 knots submerged. She carried a complement of 31 was armed with one 3 inch gun; ...
[n] - someone who upholds or maintains
maintainer noun someone who upholds or maintains; `firm upholders of tradition`; `they are sustainers of the idea of democracy`