Although Cornelius might not fully understand what Cassandra meant, or at most might suspect what she was hinting at, Lex could tell what she was considering. She was already on her way to becoming a Dao Lord.
Truthfully, Lex had no idea how long to expect such a thing to take. Each of his breakthroughs had not taken so long, but it was only after becoming an immortal that he was getting a hint of how much time these things take.
He was always an outlier, but even so, now when he began to meditate or contemplate on various laws, minutes would turn into days without notice. It was, perhaps, the nature of greater powers that even considering them took greater time.
So he was suspecting that, whenever Cassandra finally did take that leap into the realm of Dao Lord, she might find Cornelius once more and invite him to join her in her venture.
