St. Joan of Arc Girls' College, Arthur was no stranger to it.
His aunt was 'studying' there—at least nominally, Marinda's 'friend' Anna had once written to inform Marinda that there was no lady named Cassandra there at all.
As Marinda spoke of this, she kept scrutinizing Arthur suspiciously.
Clearly, the lady had misunderstood him somewhat.
Believing he was testing her fidelity.
In response, Arthur felt quite wronged and unjustly accused.
How was he supposed to know his aunt wasn't at St. Joan of Arc Girls' College!
Just like...
How was he supposed to know he was the only Muggle in the family?
They all promised to be ordinary people, but every single one of them kept him in the dark.
He wasn't some villain.
Nor was he someone unable to handle setbacks.
Even if, at the time, he knew he was a Muggle, so what?
At worst, his heart might feel some jealousy, and then, quietly strive.
Ultimately, would it lead to disaster?
The whole family wiped out?