One way is to build up the tension before the interruption. Make the interrupted person be in the middle of an important point and then have the interrupter burst in unexpectedly. Also, describe the reactions of both characters to add depth.
It's usually pretty straightforward. Just look for the options or settings within the stories app and there should be a 'block' or 'block user' option.
Well, to unmute someone on Story, you need to go to the settings related to the person's profile. There, you should find the option to unmute. Sometimes it might be hidden in a sub-menu or marked with a specific symbol. Just keep an eye out for it.
First, think about the role they'll play and how they interact with the existing characters. Then, find a natural point in the story to bring them in. Maybe have them cross paths with the main characters in an unexpected way or show up as a helper when needed.
You could start by showing them some popular and visually appealing comics. Like Marvel or DC series. Maybe start with a character they might be interested in based on their other hobbies or interests.