How did Percy get Scabbers?

[kandbmom]

No: HPFGUIDX 105283

     How did Percy get Scabbers?  We have not yet heard?  Surely, 
the "Rat" did not just appear at the Borrow and Percy adopted him.  I 
wonder if Arthur found the injured "Rat" at the scene  where Sirius 
was arrested and took him home to nurse him back to health or was he 
given to Percy be a well place DE?  I think this could be very 
important to what Percy has known all along and how he could have 
been used before Ron received the "Rat"
     Any thoughts?