Lyle was now placed at an impasse.
He couldn't kill the bastard.
If he did that, then he would need to kill not only him, but everyone that had any knowledge of him trying to poison Lyle, and even then, he wouldn't be safe.
The father knew his son hated Lyle, and he didn't really care for it since he held no love for Lyle himself. He had never tried to do anything to Lyle, but he never showed any kind of politeness when meeting Lyle, nor did he try to hide the displeasure he felt from Lyle and the fact that the two of them were ranked the same.
As an older Night Blade, the connections and influence of the man had been vast and Lyle couldn't be compared to him. His strength was also something way above Lyle's own, even before he evolved.
If Lyle was to kill his son, and he found out, then even if he knew that a Shadow was backing Lyle, he would still kill him, that much was certain.
But Lyle also couldn't let things stay the same.