That person was Alberts!
The young 'Detective' Alberts!
'How could he appear here?'
'Could it be that Alberts is involved with the Mouse Council?!'
'No, that's not right!'
'It couldn't be Alberts, it had to be...
his uncle!'
The moment he saw Alberts, Arthur's brain began to rapidly work—He was impressed by the young detective, recognizing his talent, but also noting his youth and pleasant disposition.
In the three days they spent together, Arthur had confirmed this.
Such a straightforward, inexperienced person was not what the Mouse Council would need.
Besides Alberts himself, there was only his uncle left in South Los.
Coincidentally, it was his uncle who had informed Alberts about the Mouse Council.
So the reason for Alberts's appearance at this moment was naturally to...
save his own uncle!