Captain Marvel, Jr.

Origin
One of Captain Marvel’s punches sends the villain Captain Nazi careening into a lake. An elderly man, Jacob Freeman, and his grandson, Freddy, happened to be fishing in the lake near where Nazi has landed, and, not knowing who he is, lift the unconscious man into their boat to prevent him from drowning. Nazi immediately comes to, tosses Jacob into the lake, and knocks Freddy out of the boat with an oar. The old man immediately dies, but Captain Marvel is able to save an unconscious Freddy and bring him to a hospital.

Captain Marvel changes to his regular form of young Billy Batson, and is told by a nurse that Freddy is not expected to last the night. Billy then devises a better way to help the boy: he sneaks Freddy out of the hospital and takes him to the secret underground throne of the wizard Shazam, who first granted Billy the power to become Captain Marvel.

Billy asks the wizard to heal Freddy and save his life, but Shazam cannot, and instead tells Billy that he, as Captain Marvel, can pass along some of his powers to so that Freddy can live. Shazam disappears and Billy transforms back into Captain Marvel, just as Freddy awakens. Looking up, he exclaims “Why...it’s Captain Marvel,” and is instantly transformed into a super-powered version of himself. Captain Marvel tells him that he is now "Captain Marvel, Jr.". Unlike Billy, who as a youngster transforms into an adult Captain Marvel, Captain Marvel Jr. maintains his youth and resemblance to Freddy. Additionally, hear is clad in a yellow-on-blue costume with a red cape, rather than Marvel's yellow-on-red with a white cape.

Captain Marvel informs Junior that he cannot remain in his super-powered form at all times, but that he must allow his human form to heal as best it can. With that, Freddy once again said his mentor's name and returned to his hospital bed. Freddy remains permanently lame in his left leg and is forced to walk with a crutch (although Captain Marvel, Jr. bears no such impediment). As a result, Junior sought revenge against Captain Nazi, and the two repeatedly battled over the years.