To speak of it, the reason John had bizarrely come to challenge Owen was, in retrospect, rather amusing.
John challenged Owen over Emily.
To be precise, just the day before, John had submitted a transfer request to join the 5th School, but Owen had flatly rejected it.
He didn't want to get involved with someone like John.
However, Emily's transfer request was still under consideration, and John must have been infuriated by this indecision.
At that point, John was still able to keep his composure and hadn't directly issued a Blood Duel challenge.
To provoke him further, Owen simply approved Emily's application and announced that she would become his student—he would personally mentor her, a relationship almost akin to what Catalina had with Owen.
Upon hearing this news, John completely lost it.
After all, to him, Emily was his only chance at redemption.