Simplify the following text for a Grade 6 native English-speaking person.
Original: The comic-book series Captain America continued to be published , with Rogers ' former sidekick , James `` Bucky '' Barnes , having taken up the mantle , and keeping it at the insistence of Rogers , who upon his return began operating as an intelligence agent in the series Steve Rogers : Super Soldier .
Simplified: He is also known as his alter ego Steve Rogers . Captain America had a sidekick ( friend ) , Bucky who later became the Winter Soldier .