I think that if Regulus had not been into the pureblood surpremesy, I doubt Sirius would have hated him as much as he did. We hear from Sirius that Regulus was the 'good child' of the family. Thus it can be assumed with high confidence that he was into the whole Pure thing.
I do think that Draco and Regulus have similarities. Both grew up in houses that fawned over the Dark Arts and the idea of Voldemort, disregarding whatever influence Sirius had on Regulus right now. And both liking the idea of Voldemort, joined the Death Eaters, and both got in too far.
I do think that Regulus believed his parents and was into pureblood supremacy, and the idea of the power that Voldemort held was probably very appealing. Yet however once in, I think seeing first-hand exactly what Voldemort and the Death Eaters were all about probably really made him much more aware, and THEN would be when everything Sirius had told him would start resonating. I think it would of had to start at least a little bit before Voldemort used Kreacher, because I think it'd take more then one thing to open his eyes. But maybe Northumbrian is right and that is what opened his eyes, Voldemort's treatment of someone who was close to Regulus, and then he just went to realise more and more afterward.
Were you referring to my last section? Because I wasn't really talking about his respect for Kreacher. I was more trying to say that it is possible Regulus saw joining the Death Eaters as a way to further explore the Dark Arts, that he could have been more interested in the Dark Arts for other purposes than furthering Pureblood supremacy. Mixed motivations, kind of.
Originally Posted by welshdevondragon
I suppose what I'm getting at is that if he is intelligent enough to hide his purpose of destroying a Horcrux from Voldemort (which he would have to have done to reach the cave, not an easy task to do undetected) he could be intelligent enough to hide his motives, in which case they could be slightly different to the average Death Eater.
It all depends on exactly which point in time it is, since the time period between Regulus joining and going after the Horcrux is quite short.
Ok, reading over that I've confused even myself, so kudos to anyone who actually manages to understand my crazy thought processes!
I see what you're getting at, but Regulus has been raised in a supremasist household, and unlike Sirius, was sorted into a house that values that. Where would he have learned to question the principles he was brought up on?
Also, I think Voldemort's emphasis in the beginning was very much the 'purification' of the wizarding race, which, Sirius says, his parents were all for. He also says that a lot of people were, before Voldemort showed what he was prepared to do to achieve it. So, I think this means that he built up his reputation on the premis of blood supremacy, and then showed he was prepared to use the Dark Arts, rather than the two being linked from the word go. Regulus also has cuttings of Voldemort on his wall that go back several years before he joined the Death Eaters aged sixteen. Presumably, these are about Voldemort's plans for wizard domination rather than the Dark Arts considering they're several years old. If he was more into the Dark Arts, why not have those types of articles on his wall instead?
I think it might be possible to show that Regulus was into the Dark Arts more than blood supremacy, but it still must have mattered to him given the up-bringing he had and the fact that he was prepared to join a group that wanted to put the purebloods back at the top of the table and murder countless Muggles and Muggle-borns in the process. Being exposed to all that must have had some effect on him.
Personally, I think it more likely that Regulus was a blood supremacist than into the Dark Arts, but this is just my opinion.