Prophecy - Thrice Defied?

[gelite67]

No: HPFGUIDX 113495

Does anyone else wonder what "thrice defied" means in the prophecy in 
OOP? Does that mean Lily & James and the Longbottoms refused to join 
LV three times each?  Or does "defy" mean something else? Regardless 
of what it means,why would LV give them a second or third chance to 
defy him?  Unlike DD, I would imagine LV doesn't believe in second or 
third chances.

Angie