this is very cute, anon. the teenage commitment to wanting to see the best in a sad-eyed boy is universal, and i respect it enormously.
but no. it’s not what’s happening here.
regulus serves two very interesting purposes narratively.
the first is that - across order of the phoenix and half-blood prince - he serves as the narrative parallel to draco malfoy: someone whose interest in the death eaters is inextricable from his perception of his role as a pureblood son from an extremely class-conventional family; someone who wants to be perceived as important in contrast to a rather more impressive family member; someone whose blood-supremacist beliefs are completely sincere and whose support for voldemort is completely genuine, but whose understanding of how voldemort intends to achieve his aims is hopelessly naive; someone who gets in over his head and then panics; and someone whose relationship with voldemort is seen by harry as entirely subordinate.
[he never assumes draco will succeed in his mission, for example. nor that draco will be able to outfox voldemort in any way. why he pities him is because he thinks draco’s going to be murdered by the dark lord any minute, but he also views this as - essentially - a skill issue, which wouldn’t be a problem for him…]
but in deathly hallows, regulus’ narrative purpose shifts. the revelations about his turn against voldemort become the dress rehearsal for the reveal of snape’s true loyalties at the end of the book - he’s someone who had a damascene conversion when voldemort threatened somebody he cared for, gave his life to bring the dark lord down, and did so in a clandestine way [i.e. by ordering kreacher not to reveal what he’d done] in order to protect the surviving member of the family he loved from voldemort’s wrath.
[although the idea that kreacher was his best - or, indeed, only - friend isn’t actually stated in the text. regulus is implied to be someone fairly lonely by the narrative - the photograph of him as seeker (the only player who acts alone) follows harry seeing the photograph of sirius and his friends - but all we ever learn about his relationship with kreacher is that it was kind. and, indeed, that it was similar to walburga, narcissa and bellatrix’s treatment of him - which hermione says, and kreacher doesn’t correct her.]
regulus’ second narrative purpose - along with his parents - is to underscore that blood-supremacy is a mainstream political view.
the series dispenses with this in deathly hallows, when voldemort’s malevolence becomes much more singular and the conflict narrows to the final confrontation between good and evil, but prior to this book it’s clear that the death eaters’ political rhetoric is just speaking the quiet part out loud. pretty much everyone thinks that being pureblood is better and there are too many muggleborns knocking about being annoying, they just don’t say it.
orion and walburga don’t support voldemort because they’re uniquely immersed in dark magic. they support him because they’re mainstream and conventional and conformist - while sirius, the family’s free-thinker, is none of those things and therefore not a voldemort fan. the same thing is being implied by them supporting voldemort as by vernon reading the daily mail - that they’re small-minded and conservative, but not radical. vernon would be horrified by a radical right-wing terror group who sought to destroy the status quo he values. orion and walburga pivoted away from voldemort because his violence became similarly radical.
regulus joins the death eaters, then, due to convention. he wants to prove himself - absolutely - but he wants to do so within a social structure he’s familiar with and which he and his family value. his doubts about voldemort clearly begin when it becomes apparent to him that voldemort wants to destroy the wizarding social order and build it anew.
and his best parallel here is percy weasley.
percy is - by far - the most conventional of the weasleys. his estrangement from his family in the latter half of the series is meant as a criticism of this conventionality - percy believes what he’s told and doesn’t think for himself and conforms to the group and so on - and his estrangement from his family is also clearly intended by the text of order of the phoenix to provide more context than the surface-level narrative is able to about sirius and regulus’ relationship:
“I’m just s-s-so worried,” she said, tears spilling out of her eyes again. “Half the f-f-family’s in the Order, it’ll b-b-be a miracle if we all come through this… and P- P-Percy’s not talking to us… What if something d-d- dreadful happens and we had never m-m-made up?”
percy gets written a lot by the fandom as someone who was a secret resistance fighter during the thicknesse regime. i’m afraid i’ve always thought this is nonsense - not because i think he was a death eater [i don’t!] but because i think his position, as someone who clearly doesn’t like to go against the crowd, would be to keep his head down and try to get through the war without rocking the boat.
his decision to fight in the battle of hogwarts is him rejecting his earlier conformity and taking a stand. so is regulus’ decision to turn against voldemort. and the implication of the text is that both of these decisions are reasonably abrupt “shit or get off the pot” moments.
and this is why the narrative considers them impressive.
the central theme of the series is choice - and, specifically, the choice between what is right and what is easy. the narrative wouldn’t care about snape if he’d always been a double agent, it cares because he had once sincerely believed in voldemort and then chose to do the right thing and reject him.
in the text’s eyes, then, regulus’ choice to sacrifice himself to defeat voldemort is actually much more impressive if we assume he was a loyal death eater than if we assume he saw through voldemort straight away. and notwithstanding the moral question, i also think it’s much more interesting.
