I was in the mood for some Donnie love and inspiration struck. My overactive imagine combined my love for Donatello and my love for medicine, and this was produced. I got to thinking that Don was never really an active "doctor" in the series, but it's a very widely accepted idea in the fanfiction realm that Don takes care of all of the family's medical needs. So I wrote this: my idea of how and why Don might have gained his medical know-how. Takes place after "Tales of Leo."

I do not own the turtles or any other creatures (mutated or otherwise) from the series.

TMNT

The images of Leo's beaten, bloody body had haunted Don for weeks. Long after the young leader was up and about, beginning a light training regimen, Don awoke from nightmares breathing hard and overwhelmed by a sense of dread and anxiety. Even when he went to Leo's room and sat by his bed for hours, just listening to him breathe, the fear didn't leave him.

It had been the scariest experience of his life, coming so close to losing a brother. They had been fighting for a while, but he hadn't realized the gravity of what they were involved in. Their lives were in danger every time they faced the Shredder and his Foot.

But what scared him the most was his inability to do anything about it. He was Donatello—the one who could fix anything that was broken, who could solve any problem—but when it came to what really mattered he was useless, helpless, unable to do anything except stand by and watch his brother suffer. He couldn't accept that. He couldn't live with that.

So he did what he did best. He learned. He started with the basics, reading about human and turtle anatomy on the internet. He found sites with detailed instructions on first aid, how to give stitches, CPR, and other basic procedures. When the internet failed him, he managed to find books, often buying them through April. He learned how to stop bleeding, reduce fever, administer drugs and IVs, and bandage sprains and breaks. He educated himself on the treatment of various illnesses and began to stock his lab with a comprehensive collection of medical supplies. A portion of his lab was carefully converted into an infirmary, complete with a bed and a slightly out-of-date AED.

The next time one of his brothers was injured, Don was ready. They had all been awed by his sudden wealth of medical knowledge and ability. All of them, even Leo, who understood him better than any other member of their family, had assumed his recent obsession with medicine had been a type of post-traumatic stress disorder in the wake of the Shredder's attack and Leo's near-death experience. But as he expertly staunched the flow of blood from Raph's shoulder and confidently stitched him up, they all looked at him with a new sort of appreciation—and respect.

After that, his brothers always came to him with their injuries and battle wounds. He became the family doctor; his expertise was something they could always count on. Leo often worried that he would feel taken for granted, but Don always reassured him. It meant more than he could express that he had something so important to offer his family, his team. He no longer had to watch as his brothers suffered and bled. He could help them. He could do something. Don wouldn't have traded that feeling for anything in the world.