[HPforGrownups] Re: Snape: ESE or DDM? Power of Love

[Bart Lidofsky]

No: HPFGUIDX 167152

From: Lydia French <lydiafrench at gmail.com>
>Snape didn't come to Dumbledore until after the attack! You see? Snape, 
>then a DE, told his Dark Lord about the part of the prophecy that he 
>heard, believing that voldy would go after a stranger whom Snape 
>neither knew nor cared about. 

Bart: 
First of all, it has been made pretty clear in the canon (including Dumbledore's testimony in the Pensieve flashback) that Snape joined Dumbledore while Voldemort was still at the height of his power; about a year before the attack on the Potters, possibly before Harry was born, although probably not long after (Harry's birth marking him as the target). Although canon is not explicit here, it was almost certainly Snape's info that caused the Potters to go into hiding.

However, while the canon implies strongly that Voldy's interpretation of the prophecy was the trigger that brought Snape to the other side, there HAS to be something more that caused Dumbledore to trust Snape. 

Bart