There might be a fanfiction where the reader has a broken heart because of some misunderstanding with one of the turtles. Maybe the reader thought they had a special connection with Donatello, but then sees him with another character. This 'hurt reader' situation can lead to a lot of emotional turmoil and character growth as the situation unfolds.
To effectively write a 'hurt reader' situation in TMNT fanfiction, you need to focus on the emotions. For example, if the reader is physically hurt, describe the pain in detail. Say things like 'The pain shot through the reader's leg like a bolt of lightning, making them cry out in agony.' This makes the reader of the fanfiction feel more connected to the situation.
One possible scenario could be that Mikey gets hurt during a fight with the Foot Clan. Maybe he underestimated an opponent and got a nasty cut on his arm. His brothers would then rush to his side, with Donnie trying to patch him up as quickly as possible while Leo and Raph stand guard, ready to fend off any further attacks.
In many 'TMNT Mikey hurt' fanfictions, a common plot element is Mikey's own attitude towards his injury. Sometimes he tries to be brave and not show how much pain he's in to not worry his brothers. Another element is the search for a cure or solution. If he's poisoned, they'll look for an antidote. If it's a physical wound, they'll try to find medical supplies or a way to heal it. And there's usually a lot of brotherly bonding as they take care of Mikey.
Protecting what's been hurt in TMNT fanfiction can involve having the other characters show more empathy and understanding. Or, you could introduce a magical element that shields them from further harm. It could also be interesting to have the hurt character discover their inner strength and use it to protect themselves and others.
Raph would be the first to show his concern through anger. He'd be mad at himself for not protecting Leo better and also at the situation that led to Leo's injury. Mikey would be visibly distraught, constantly by Leo's side trying to cheer him up. Donnie would be all business, using his scientific knowledge to figure out the best way to treat Leo's wounds and help him recover.
One common scenario could be during a battle with a powerful enemy. For example, the Foot Clan might set up a complex trap and Leo, being the leader, might rush in to protect his brothers and get seriously injured. Another could be in a training accident. Maybe he's trying a new and difficult move and it goes wrong, resulting in an injury.
In a fanfiction, Mikey might get hurt during a mission to infiltrate a Kraang base. He could be detected by security systems and get zapped by some sort of electric defense mechanism. This would leave him weak and in pain. His brothers would need to carry him out of there and find a way to reverse the effects of the zap. They'd be desperate to get Mikey back to his normal, energetic self.
One common theme is protection. The TMNT are known for their protective nature, and in these fanfictions, they will often go to great lengths to keep the pregnant reader safe from various threats.
They would be very protective. Autobots are known for their sense of justice and protecting the weak. So, they would immediately surround the reader to shield them from any further harm. Bumblebee might be the first to approach the reader gently, trying to communicate in his beeping way to let the reader know they are safe now.