Things that will come into play later.

[wildfire_517]

No: HPFGUIDX 79693

Nox asked:-

> >>Does anyone actually know what becomes of a dementor once it has 
been charged by a patronus? Is it destroyed? Can it return? Is it 
immaterial as there are so many of them and a constantly new supply? Does it just disapear and end up somewhere else (think Tartaru or somewhere)?<<<
 

Of course I don't have any reference materials handy, but I believe 
that a Patronus only drives the dementors back.  There is never any 
mention of them being destroyed, whether it is the singular boggart 
posing as a dementor or the hundreds attracted to Sirius, Harry and 
Hermione by the lake.  

Now, since the key requirement to producing a Patronus is to think 
about a moment of extreme happiness, I would guess that the reason 
dementors shie away from one is that the emotions produced cause 
an "overload" in their circuits.  The happiness, which they would 
normally feed off of, is too great for the dementors to bear, driving 
them away.

Following that, it would seem that they are forced to flee the 
scene from the emotional overload caused by the Patronus, but could 
return at a later time, when the power (emotional signature?) of the 
Patronus has diminished.

   Wyld