Oni no Ou to Chigire - Chapter 5 Pg 101

If just being outside made him react that violently he really may have died if he had gone inside the house. He didnt want Tokimori to die, so the only way he could be by his side was to make himself look small and weak. He had become disheartened when it failed over and over again, making his days rough. He would want to see Tokimoris face to cheer himself up, but when he would peek through the window, Tokimori would scream, faint, and break out into a fever. Since he was only able to get close to him when he slept, Yato would sit by his pillow, put a finger to his forehead imbued with sweat, and absorb the fever tormenting him. A faint warmth would move into this fingertips. It pained his chest that he was so weak even just this small amount of fever could make him pass out like that. Tokimori didnt know about any of that. Yato would tell him about his hardships and devotion to him one day. If Tokimori accepted Yatos true self anyway.

kh.

Yato took a step toward Hoshiai in order to show him the same pain he felt a bit, but he heard Tokimoris voice calling to him. Since demons and their masters share each others blood, they can hear their demon masters voice right away no matter how far apart they are, no matter what theyre doing.