This has been happening more often ever since Lyle reached the Grand Realm. Previously, he would sometimes feel some urges, like back when he had tried to kill Priscila, but that was it, they were only urges, nothing more.
Ever since he had reached the Grand Realm, however, Lyle was feeling more of an influence on him, he was sensing that something deep within him was trying to make him do things he normally wouldn't do.
There was a voice inside his head at times, one very faint, a voice that spoke words that Lyle's couldn't hear, but he could understand them.