Ryuk could feel it—the absolute disregard for his existence.
He was always able to sense it when someone had no regard for him. It was like a magnet that attracted him instantly.
The Frost Wyvern Lady had arrived with her full pressure enveloping him particularly, or else Seraphis who was much weaker, would have collapsed from such a wave of power.
But she remained standing, which showed she wasn't being targeted by the aura Ryuk was feeling—it was Ryuk alone.
Then she had attracted Isha to herself, directing the feeling of her being under her control.
To a Beast Tamer, this would have been an absolutely hair-raising scene.
One knew well that a Beast Tamer's strength was his beast.
If a beast was under the control of another person, then the Beast Tamer was as good as dead, as the beasts might be reluctant to fight one they were so familiar with.
Ryuk knew he was far from a Beast Tamer, but he also knew others would naturally see him as one.