How about a twist?

[steven1965aaa]

No: HPFGUIDX 159978

--- In HPforGrownups at yahoogroups.com, "abergoat" <adescour at ...> 
wrote:
>
 
> The bizarre thing is why does Dumbledore tell Snape he needs to
> investigate his own house? Dumbledore suggests in the tower he 
knew it was Draco along, which fits with your theory that Dumbledore 
was insisting that Snape perform the task the vow required.  So what 
was there to investigate? Draco refers to 'better help than you', 
does Dumbledore want Snape to figure out who that help is? Is Snape 
not really trying? How does this fit into the vow? Exposing 
the 'help' would actually be going against Draco...so I guess that 
is a point in favor of Dumbledore not knowing about the vow. But I 
don't really buy it.
> 
> Anyone have ideas what the investigation was about?
> 
>Steven1965aaa:

A thought just occurred to me and I apologize if its been mentioned 
before, but is it possible that "your house" did not refer to 
Slytherin, but rather referred to Snapes house at Spinners' End?  I 
have wondered why JKR shows us that Wormtail is living there with 
Snape, what purpose does that serve in the story?  Maybe DD wanted 
Snape to make some investigation with respect to Wormtail, or maybe 
something else is going on at Snape's house, some other death eaters 
living there?