Justin's panic attack in 13 Reasons Why fanfiction could trigger a series of events. It might make him confront his inner demons, or it could bring people closer to him who he didn't expect. The possibilities are endless depending on the author's imagination!
Well, it could vary depending on the specific fanfiction. Sometimes, he might get support from friends to calm down.
In many cases, Justin's panic attack in fanfiction leads to character development and deeper exploration of his emotions. Maybe his friends help him through it, or it causes him to make some big life decisions.