Writing Games: Second Banana

Some people don't mind playing second banana to
someone equally or even more impressive than themselves;
is the protagonist of your current story one of them?

    We all know what it means to be a second banana, right? To be the Number Two person in a business, ranked just a little lower than the Number One. It's not a bad position to hold; in fact, it's rather distinguished, and the work is satisfying when you love it.
    But some people really can't bear playing second fiddle. Most of the time it's pride, but I think there are also situations where, being used to being in charge or flying solo, the person has to really work to let go of some instincts, and learn to submit to the leader.
    And since so many other things in real life appear in fiction, this second banana scenario must also be applicable to characters in a story, right? If a protagonist finds him/herself suddenly uprooted from their place in the spotlight and put on the sidelines, they'd probably have some difficulty adjusting. So what if that happened to the protagonist of the story you're writing now? What if someone just as (or even more) talented, interesting, unique, and virtuous came along and took charge? And what if that someone is the protagonist of another story?
    Therein lies the writing game! :) Taking a main character from a different work (an old manuscript, or a well-known, published story), putting them in a scene with the main character of the work you're currently writing, and making it so that the protagonist of the current story has to act as the sidekick.  What happens then? Would s/he feel content to yield to the other leader, or would they feel uneasy about not having control for once? Would they be okay with doing whatever the other suggests, or would they occasionally defy an order? Would they accept the other as their leader at all?
    They're interesting things to consider because there's definitely something that differentiates a protagonist character from a sidekick. Sherlock Holmes could definitely not fill the shoes of Doctor John Watson, nor vice versa. Their personalities and other aspects make them fit for their own roles. So putting a protagonist character in a situation where they try to play the role of sidekick could showcase their qualities that are better suited for leadership. If the character is antsy about not having control over what they're doing, it would indicate a confidence in their own decisions. And if the character, even when they approve of the leader, finds him/herself ignoring commands they don't trust completely, it shows that their concern is more focused on doing the job correctly and safely rather than pleasing someone else.
    So, what do you think? Would the protagonist of your current work do well as a second banana? Or are they too independent?