I was writing a big giant set piece chapter some time ago, trying to make it more streamlined and more exciting than it had been before. It was a serious challenge because it involved a big ceremony - the Accession Ball - that had to happen in a particular way, and it was sort of one thing after another after another. Lots of events, and a bit of internalization by my protagonist. Not boring precisely, but you had to be able to buy in. Some readers I knew would start skimming.
So I added a sidekick.
I had a convenient character available. Tagaret (my protagonist) has an eleven-year-old cousin, Pyaras, who appears in the story and tries to become a part of his gang because other kids are abusing him. In the first draft of the chapter, I had Pyaras get upset and be kicked out of the Ball, and Tagaret went in alone. In the new draft, I had Pyaras go in with Tagaret.
Sidekicks are great, because they do several things.
1. They ask questions.
A younger kid, or someone who isn't an expert, can be confused by different points of what is going on, and create realistic reasons for your main character to explain things (or for bystanders to explain things). This spares you a lot of "show don't tell" effort by creating a realistic context for telling.
2. They inspire your protagonist's better nature
Tagaret is expected to look after Pyaras and make sure he's okay. Having him around gives Tagaret a chance to think about someone beside himself. It helps him be more altruistic, less self-centered, and also can create fabulous opportunities for him to make difficult decisions. "Do I leave Pyaras here and go out to see that girl I've been admiring - even if it means he gets in trouble? Or do I give up my chance with the girl and protect Pyaras from the bullies?"
3. They can create diversions
In the new draft of my scene, I decided to reduce the feeling of "lists" by having Pyaras act up. Now, be aware that you shouldn't just have people act up randomly - it has to fit in with what you already have going on. Pyaras has already been getting bullied by kids who think he's too big and strong for his own good, and more like one of the lower-caste soldiers than he is like a nobleman. Thus, when one of the soldier caste people appears in the ceremony, someone in the audience decides to needle Pyaras, and Tagaret has to stop him from trying to start a fight right in the middle of the party. This simultaneously advances their relationship, and Pyaras' emotional states, and it also lets me skip over some stuff in the ceremony that readers might find repetitive.
4. They can draw out your protagonist
Tagaret is not a super-introverted guy, but the Accession Ball scene doesn't give him a lot of chances to interact with other people, especially during the ceremony. Putting Pyaras with him helps because he can whisper to him and interact in an external rather than an internal way. Especially if the person you're working with is the strong silent type, giving him or her a companion to talk to will really help keep those scenes from becoming too slow and introspective.
It's something to think about!