A loyal sidekick is a person who is always there to support and help someone, usually a leader or main character. They are trustworthy and remain by their side no matter what happens. Full definition
While Depp did not hold the title role, instead playing the Lone Ranger's loyal sidekick Tonto, he still took top billing and a lion's share of the marketing over The Social Network's less experienced Armie Hammer. (dvdizzy.com)
He is now Dr. Barnes» loyal sidekick spending his days in the hospital with «Dad,» lounging in whatever sun spot he can find or stealing our Office Manager's chair for a nap. (my4pawsvet.com)
With an insanely funny set of characters, including loyal sidekick Gus the Guinea Pig, Major Magnet's off to save the world from Colonel Lastin, without even realizing it. (indiemegabooth.com)