All the meaning behind Frederick Melvin was for that one nightmare "with Justus in existence".
It could be seen from the nightmare.
From the very beginning, it was Justus whom Professor Gray had his eye on... and not Frederick, who had reached the silver rank at such a young age.
Because since that time, Professor Gray already knew.
——Frederick Melvin would eventually be killed by his own hand.
Therefore, teaching him was a meaningless task.
Murdering Ingrid in front of Justus.
And later, murdering Frederick.
Everything was for the purpose of creating an incredibly real nightmare that could deceive the eyes... designed to make Justus lose himself in the nightmare, confusing dream and reality.