Slytherin house

[potions_mistress_13]

No: HPFGUIDX 191679

Eric:
"Regulus, you may note, was able to glag down all of that horrible potion, which was more than Dumbledore could do unassisted, all by himself.  He died a member of the Clean Plate Club!"

Elena:
The exact effects of the potion are not clearly spelled out. In HBP, Dumbledore's cried out "It's all my fault, all my fault," "Please make it stop, I know I did wrong, oh please make it stop and I'll never never again...", and leter, "Don't hurt them, don't hurt them, please, it's my fault, hurt me instead..." In DH, Harry tells Aberforth that the potion caused Albus to relive his sister Ariana's death. 

The potion may cause one to re-live one's worst memories, as do dementors. Recall that dementors affect Harry more than his classmates because he has comparatively worse experiences in his past. The same could be said for Dumbledore. At the time he drank the potion, he was an old man. Regulus, on the other hand, was at most only a few years out of school. Perhaps Regulus was able to drink all the potion because he had fewer horrifying experiences compared to Dumbledore. 

Elena