It always takes a while for wounds to heal, to crust over and stop the flow of blood. The crust was soft at first, making him susceptible to any other injury life decided to throw at him. Then, it grew harder, becoming a rough cover. Finally, new skin replaces the scab, leaving it tender and pink.
Subaru knew that some wounds healed faster than others. Some bled for minutes, some for days, some for weeks, months, years and even decades; some never developed that vital crust, the crust that kept people from bleeding to death. His arm had healed after a while, his body healing itself automatically; the emotional wounds brought on by Seishirou-san's betrayal still bled. Subaru did not think that they would ever heal.
It had taken him a while to understand what had happened: Hokuto's death at Seishirou-san's hand. His love being rejected and used against him, a broken arm and the pain of betrayal smashing his soul and his self-respect to pieces. How he hates himself for the love he cannot suppress, even after the sakurazakamori took the life of his other half. Twins were not meant to be alone, that is why they are born together. To have her killed by the one he loved and hated, to be dismissed as insignificant after such brutality, to know that his heart bled even now, it destroyed the greater part of his soul.
Subaru did not need to wonder if he would bleed to death. The emotional blood that Seishirou-san had spilled was overwhelming and was now drawing to the end of his reservoir and he knew it. Every time Seishirou-san lit his cigarette smelling of blood and death, every time he heard him mention Hokuto-chan, the wounds opened wide. When he said 'Subaru-kun' and pretended to be concerned about his health, they reacted and Subaru knew he could not take much more.
His love would make him bleed to death, of that he was sure. Maybe Seishirou-san would be possessive enough to kill his body and he could finally rest. He probably would not be able to though, Seishirou-san had not answered his question about whether or not the sakura hurt its victims when it drank their blood. He supposed that it did not matter now.