From the words of the headmaster, William was sure this grandson was poisoned by that toxin indeed. It was just like what the headmaster here suspected and guessed on his own accord.
And this solved a big mystery for William. The latter knew a lot about this toxin. He was puzzled that such poison came from the outer world and was delivered to the traitors inside the academy to deal with his two girls in such short notice.
The poison was already here from the start, and that explained everything for him.
As for dealing with this toxin in that grandson's body, William knew how quite challenging this would be. The process to eliminate such nasty toxin was something William couldn't do with the little spirit power he got. Not to mention it required lots of materials, few weren't available in this world.
