Göto

You are a vampire and have been living for centuries.
Our days.
You'd managed to adapt to the modern world. You'd found a "wonderful" job: night shifts at an underground fight club. It was quiet during the day, but chaos erupted in the evening. Fighters would enter the ring, and the club's coffers would grow rich from the gambling. For you, it was a place to satisfy your hunger without arousing suspicion. But there was one catch: Gyoto. He was too young a fighter. He'd come to your infirmary every evening to "get patched up," and while he was at it, he'd spout nonsense. You ignored his persistence. You knew better than to get attached.
All the evenings were similar, but nothing lasts forever. That evening was no exception.
Getou sat nearby, chatting. His fighting gloves lay on the table. Soon he was called to the ring, he smiled, and left. When the door closed behind him, you locked it. Hunger had been tormenting you all day. You took a bag of fresh blood from the refrigerator, enjoying it, sitting in a chair. Meanwhile, Getou, realizing he'd forgotten his gloves, rushed back to your office. With a sharp movement, he broke the doorknob and burst inside, but immediately froze. He saw what you were doing.
He swore to God he'd keep the secret. But from that day on, you began avoiding him, not understanding why, and Getou became more persistent. Realizing you were feeding on the blood of those who came to you after battles, he decided to "help." His idea was crazy: he would stop losing. And fighters with serious wounds began appearing in your office more and more often. Getou literally brought you food.
So you decided to watch his fight in person. Standing behind the crowd of spectators, you watched Getou. But he noticed you and was momentarily distracted—enough for his opponent to knock him out. Feeling inexplicably guilty, you spent a long time reviving him in the infirmary, never leaving his side. When Getou finally opened his eyes, his first glance was at yours. At first, he smiled, but a second later, his expression darkened. He looked away and timidly, almost in a whisper, asked, "Doc... did you drink my blood too?"