User blog comment:Abranon/Why didn't Regulus Black do more to contribute to Voldemort's Death?/@comment-71.21.212.151-20120804152910

I don't think people really understand what you are asking here. First, the books indicate that Regulus could have known how the potion works, because Kreacher was forced to drink it before Voldemort put the Horcrux in there. Second, Regulus knew that the potion compelled Kreacher to drink the water in the cave, and that once he tried to do so he was grabbed by the things in the water (he did not know exactly what they were). Third, from his note Regulus appears to think he is going to be able to destroy it, so he did research how to do so, he just didn't want Kreacher to know exactly what was going on, so as to protect his family.