Life Debts was Why has DD never suggested Snape thank Harry

[potioncat]

No: HPFGUIDX 117537


Ces wrote: 
> Snape is at least honorable in the fact that he is paying off a 
> wizard's debt to someone he hates.  Perhaps he's doing it so he 
can 
> hate James in peace - that's his decision and he has to live with 
> it.  But he is paying off that debt to someone who is only seeing 
the 
> bad in him.  Who knows what a little thanks from both to each 
other 
> could do.
> 

Potioncat:
I think, but I don't remember who I stole this idea from (oblivate 
seems to have worked poorly and backward at that) that there is no 
such thing as a Life Debt. 

I can't find the cannon where I hide my copy of SS/PS, so I can't 
quote it. But DD says something along the line of 'having a strange 
idea that he owes your father a debt for saving his life.' Harry and 
almost all of us have taken that bit of conversation and worked out 
an elaborate idea of how and when Life Debts are formed.  But I 
don't think they exist at all. 

There is one other (I think only one) time that it is mentioned in 
canon, and that is when Harry tosses it up to Snape and Snape 
insists that James was in on the prank.

Does anyone who is better prepared and more persuasive have any 
ideas?