Potters' choice of a secret keeper

[jferer]

No: HPFGUIDX 43508

Millergal(Christy):"Now surely there were other people who were close 
to the Potters after school. They could just as easily been suspected, 
Sirius merely thought Lupin because he was probably in the habit of 
thinking of the four friends."

Likely, IMO, you're right. And there's something else someone 
mentioned in this thread - Lupin is vulnerable. what if LV *did* offer 
him a cure for his lycanthropy? OR threaten to reveal his lycanthropy 
to the school at large?

It's a fairly settled principle of security that people with 
vulnerabilities, are, well, vulnerable.  They don't like people with 
secrets. Is that a prejudice? It sorta is, but it's not rational to 
ignore a risk factor when your life is at stake.  I can imagine (and 
hope, for his sake) Lupin advising the same thing. He and Sirius were 
probably on the front lines against Voldemort and shouldn't have been 
exposed to capture anyway.