The whole team would experience a range of emotions. JJ would be concerned not only for Morgan but also for how the team is handling it. She might be the one to try and comfort Garcia. Prentiss would be angry. Angry at the shooter and also at the situation. She would be determined to bring the person to justice. As for Morgan himself, he could be feeling a mix of pain, fear, and determination not to let this be the end. He would be thinking about how he can get back to the team as soon as possible.
One common theme is the team's unity. When Reid gets shot, the team comes together, showing their strong bond. They support each other and are determined to find out who hurt Reid.
One possible storyline could be Derek's struggle to recover both physically and mentally after being shot. His team members might be deeply affected and rally around him, with each dealing with the trauma in their own ways. For example, Reid could struggle with guilt for not being able to prevent it, while Garcia would be constantly by Derek's side, using her tech skills to help find the shooter.
Perhaps it's an insider within the law enforcement or criminal justice system who has a vendetta against the BAU. Maybe they disagreed with the way Derek and his team operate and decided to take matters into their own hands. It could be someone who feels that the BAU has too much power and is trying to send a message.
One possible plot development could be the team's reaction. They would be in shock and immediately spring into action to find the shooter. Garcia might be the most affected, as she and Morgan are close. Another development could be Morgan's struggle with his injury. He could have flashbacks of past cases or his own traumas while he's in the hospital recovering. And finally, the hunt for the person who shot him could lead to a new and dangerous unsub discovery.
Fanfiction.net could also be a great source. It has a large collection of fanfictions. You might need to sift through a bit more compared to AO3 as the tagging system isn't as refined. But if you search for 'Criminal Minds' and then look for stories specifically about Morgan getting hurt within the search results, you can find some interesting ones.
Hotch would be very focused and determined. He would immediately start coordinating the investigation and ensuring JJ's safety at the hospital. Reid would be distraught but would use his intelligence to analyze the situation and try to figure out who the shooter could be.
Rossi would be using his years of experience to analyze the situation. He might be the one to offer the most practical advice on how to approach the investigation. And Penelope herself, even while injured, would be trying to keep the team's spirits up, cracking jokes through her pain, which would make the others both laugh and worry more about her at the same time.
It shakes up the team dynamics a great deal. The team members would be worried about Hotch's survival, which could make them less focused on their regular tasks at first. They might also feel a sense of guilt, wondering if they could have done something to prevent it. Some might become more protective of each other in the wake of the incident.
One possible direction for the fanfic could be a sort of 'what - if' scenario. For example, what if Reid's injury had long - term consequences? It could change his role in the BAU, his relationships, and even his approach to solving cases.