Wounds are usually mended with magic and then held together by some means until they heal. The healing process may take quite a while, but many saw it as the only way to treat such injuries. This fact holds even more truth in the context of internal injuries. Healing magic may not be enough under these circumstances. Other methods became necessary. The first one to discover and successfully perform this new method of injury treatment was an earth pony named Big Heart.
His wife, a unicorn named Sweet Heart, fell a great distance from a tree she was pruning. The injury caused one of her rear leg bones to fracture and break, resulting in its protrusion from her flank. The medical emergency ponies were called right away but all they could do was stop the bleeding and graft skin over the protrusion. They told Big Heart that she would live a while longer, but there was nothing that would stop her imminent and inevitable death. She was now bound to contraption that pained her, but kept her leg aloft enough as to not cause further injury. It was not something that would ever make her able to walk again, only a way to prolong her life by days. Big Heart was distraught, but kept by Sweet Heart's side throughout for he loved her so.
In the days he spent with her, Sweet Heart could see his vigor diminishing. She understood why. The years she had spent with him made her well aware of his underlying conflict. Big heart was always ready to cheer a room, yet he was hardly able to face her with a smile these days. She knew of a remedy to his times of sadness. She went through the process that she needed to only have done a couple of times before. She cupped his hoof in hers and asked him, "How large is your heart?". After shaking away the shock of her sudden yet familiar question, he tilted his gaze down to hers and gently replied, "Big." "Big enough for me?", she queried. With his eyes giving their best impression of a ready-to-burst raincloud, he shakenly replied, "Yes my Sweet. There's always room for you inside." She nestled her head under his. She noticed he was still very rigid, but seemingly stoic and calmer than he had been. She looked up to him as he stared off to something she could not see. She didn't find out til later, but he was envisioning an idea.
As the gaze into the planes of his mind fell, Big Heart muttered back the words he had just spoken. He mumbled them over and over with emphasis on the last word. "Inside!" he exclaimed. He apprehensively averted his eyes to her curious stare for a brief moment. While looking at the ground, he asked her, "If there were a way for you to stay with me longer, would you risk the last moments of your life?". "Even...", she started, "e-even if there wasn't... I'd risk anything to make you feel more hopeful about the situation my love". "I have an idea", was his reply. His eyes were stern with conviction. He was about to do something nopony else have ever done in order to hopefully save his love. It was all he could do to keep himself going, especially with Sweet Heart's health deteriorating so rapidly before his eyes. It was a foul happenstance that he hoped no one he knew would ever be able to relate to.
Sweet Heart's last day was upon them. Big heart had made all the preparations he could with the guidance he preeened from the staff of the hospital. They thought of the couple's frequent visits as desperate attempts to gleen information about obtaining a few more moments under the realm of Celestia and Luna's heavens. The true use of these techniques were privy to everyone but the Hearts. They were going to try and treat Sweet Heart's ailments from inside her. Big Heart had practiced with a skeletal replica of a pony that had hay, grass, and rope overlaying the rear flank's bone structure. In one night, with the help from an anatomy book and his slumbering wife by his side, he memorized everything he could that pertained to what he was about to do. He could not have been anything else but absolutely ready for every possible contigency foreseen or otherwise. Sweet Heart was nervous but knew of nothing but trust for his ability. Hoping for nothing but deftness in his hooves, she layed down and cast herself to sleep with what little magic her feeble body could muster. They were ready.
Big Heart had proposed that they could fix the bone if he were able to get inside and rearrange it's structure so that it were as whole as it could be again. This would also make it so that magic would have a greater effect upon healing her injury. The rest would be left up to her body. He worked at a pace comparable only to the Greatly Loyal Rainbow Dash's Light-speed Rainblitz Strike. He was able to accomplish this feat by outfitting Sweet Heart's sling with intricate machinations that allowed him to work as if his thoughts controlled their every action. HE could not stand to be without her for long knowing that his last moment with her was upon them. He knew it would objectionable to any conventional pony to open up an old injury, but working inside of the wound was the only option he could think of. An attempt at the impossible was all he wanted, it was all he had left.
Sweet Heart's leg was fixed as far as anypony could tell. Restructuring her bone to resemble what it had been formally allowed the magic essence inside of her to repair it further. This magical redirection had an unforeseen side effect. The unnatural magical behavior of her body both cried out to and forsook Death itself. In what He perceived as the Hearts' insolence, her wound was ravaged with His touch. Black bolts shot out from around her former gash. The stitches that Big Heart had sewn on Sweet Heart were underlaid by a menacingly black scar. Big Heart heard painful wails from his wife that gave him both hope and despair. He was glad that she was awake again but was frightened by the events that had just taken place. He was unsure whe ther the operation had been successful at this point or not. Her body seemed to be wracked with great pain and all he could do was stand witness and hope to be able to deal with the consequences of his actions. All he said the whole while was an odd, but common, phrase with unknown origins that suggested that mistakes may happen but we are to make the best of them and move on. "Derpy is best pony".
Sweet Heart stared viciously into Big Heart's apologetic eyes. She looked as if she were going to get up from her ordeal and slay him. If not for the process at hand, it is almost certain that she may have. However, if not for this ordeal she would not have any reason to. Throwing her head back with her chest heaving upwards suddenly from the bed, she screamed and gasped for relief. Big Heart had not seen her in as much pain, he bargained, since the operation he had to perform upon her almost 2 years ago that had left a black scar across her cutie mark. He could only think to himself, "Gee, Life must hurt as much as Death".
Big Heart and Sweet Heart became outcasts of society because of their encounter with Death. The black lightning was apparently evident to many inhabitants nearby. It had culminated and lingered in the skies for a period before vanishing into the sky. There were rumors abound that Big Heart had soemhow tapped into dark magicks in order to heal his wife and that the unnatural scar was evidence enough. They lived feeling as outsiders wherever they went. They lived in infamy. They were never outright rejected, but they also hardly ever felt welcomed.
As they were quickly ushered out of the hospital with their newborn, which they named Heavy Heart, a grieving mare approached them. She told Big heart that he was her last hope. Knowing her pain from his previous experience, he agreed to help her. She told him that her husband had an untreatable broken rib that was aimed at and threatened his heart. Working together, the Hearts were able to quickly heal the mare's husband with few complications. Big Heart's knowledge, along with Sweet Heart's newly skillfulness acquired from her former handicap, allowed them to achieve huge success. They waited anxiously. Sweet Heart looked nervously at her scar and back to her patient. They waited. There were no signs of Death. The mare thanked them and told them that they had been wrongfully treated if that was all they did. She told them that they should be blessed for their deeds instead. As they left her house that night, a bright white light let out. They did not think much of it more than a thanks for their service. Thus, the Hearts gained a reputation for their work. It remained a mystery to many and was still regarded as dark arts. Death's presence never appeared before them again, but they still anticipated him. They became acquainted to living on the fringes of society. Nopony sought them out unless it was dire.
Growing up mostly in isolation, Heavy Heart learned from his father and mother. He quickly became quite capable himself in their craft. He learned by observation and practiced upon the same skeletal model his father had. It had become more intricate throughout the years and became completely structured to mimic an actual pony's anatomy. His talents quickly emerged as a heart-shaped cutie mark with a heavy black outline around it. It signaled his proficiency for protecting life. His parents were wary of the black outline, but they accepted his talents and entrusted him with the task of furthering his studies. With a heavy heart, they bid their son farewell until his return.