There's one character of this series who's never debuted...at least, not yet. Out of all of them, I like him the most, in terms of his origins. It's taking an already stretched concept and stretching it even further...but honestly, I've been afraid of how you all would react to him. This snippet may not fully explain him, but it does set up most of the explanation.
It was hard for him to believe that the off-handed conversation they'd had not hours before had his friend's life.
He couldn't even remember how they'd gotten on the subject of the blood types. One minute, they'd been sitting outside the church, talking casually, and the next, they'd been comparing blood types. Markus was a universal donor - Noah? A universal recipient. The young Italian had laughed and pointed out the coincidence. They'd talked for a few more hours, taking advantage of one of the rare days of calm in this era of losing war.
Then the air had begun to hum with the sound of engines. Markus had realized what was happening first, and dragged Noah off the bench, urging him to run; to get to shelter. He'd sworn the other had been right behind him, but when he'd reached the shelter of a street-side cellar and looked back, Noah was forty feet behind him, assisting an elderly man who'd been knocked down in the chaos that now reigned in the streets. Markus had been three steps out into the street to run back when the world around him exploded.
He later found out later that a British bomber had dropped a payload on a storefront three miles away. The shockwave had knocked Markus clean of his feet, and dominoed several buildings…including the church he and Noah had been sitting outside. The street had been flooded with blood, dust, and rubble, and it had taken Markus five hours to dig through the mess. He found the old man before he found Noah. At least the poor soul had died from the concussion blast, and not the rubble avalanche that had buried him.
His heart racing, Markus dug through shattered bricks and glass, leaving gruesome red handprints on everything his bleeding fingers touched, until his fingertips encountered skin rather than rubble. Nearly sick with relief, Markus pulled Noah's limp body from the mess, dragging him clear of the wreckage before he all but flopped to the street. Cradling his friend's unconscious body, Markus groped desperately for a pulse. He found one, but it did little to calm his fears.
Blood was pouring from Noah's head and limbs, and there was no way Markus would be able to stem the flow by himself. The German staggered to his feet, clutching his human friend, and staggered off as the air raid sirens finally died down, replaced with the sirens of ambulances and authorities. He couldn't waste time waiting for an ambulance. It would take them too long to get across the mess of the street. Noah would die before he could get help! St. Hedwig was nearby….if it hadn't been destroyed in the raid.
God, Noah had been so pale by the time he'd scrambled through the hospital doors. Everything had become a blur, up until a question from a doctor had triggered the memory of their earlier conversation. Markus had volunteered immediately, and he'd been hooked up to the appropriate needles and tubes before he could blink. The blood loss had been dizzying, and he must have passed out at some point, because his next memory started the next day.
To his utter joy and relief, Noah had been alive. Unconscious and frighteningly pale, but alive. The nurses had left Markus in the room overnight, and they came in to check on the both of them halfway through the day. The young Italian was still at risk of catching infection from his other injuries, so the nurses asked Markus to hold off on visiting until the threat had passed. Noah remained in this precautionary quarantine for almost six months.
Markus obeyed the nurses…to a degree. He never visited Noah in person again…but he paid messengers to deliver bouquets of yarrow and yellow, white and violet tulips to the young Italian every day. They held a deeper meaning for the German, but he never got a chance to explain it to Noah. He'd fully intended to return to the hospital once Noah had recovered enough to stand a visitor…but he never did.
And to this day, Markus still had no good excuse.
Short, and with as much (attempted) historical accuracy as possible. Honestly, I have no idea what happens when someone needs/has a blood transfusion, let alone back then. My intel comes from the Internet, and I'm sorry if it's not exact.