hmm revenge is such a broad word... i'm definitely a lot more sympathetic with natsume when it comes to exfine and the eccentrics. i think natsume's feelings towards them are justified and i like reading him be sharp towards them. this is just sort of a spilling of feelings, sorry if it's hard to read, but...

if by 'the revenge he should have proceeded with' you mean him taking the stage as the five eccentrics during the war, i mostly share similar worries as his niisans... i worry that it might've stoked the fire in a way where emotions would have run higher than ever and somehow bite the eccentrics in the back, i worry that it'd result in a division within the school that would've pitted the sides against each other, i worry that it'd result in more actual death within the school... i don't agree that its the ending that the eccentrics deserved, and believe at that point they were beaten into a corner that they didn't have much choice fighting back in, and that what ex-fine did was still forgivable. but i understand wataru and i understand rei when they were concerned about what would happen if they pulled through it... like in natsume's head, he was convinced that it'd be a full turnaround and that everyone would be able to understand and love his niisans, but i think the result would've been a lot more complicated knowing how cruel life tends to be

Altered goes a little into natsume's his feelings regarding his revenge and trying to unearth what he truly wants. and it's shown that above all his feelings of hatred and revenge, what he wanted most of all is to be able to stand up for themselves alongside his niisans and perform alongside them. and OO was able to grant him that privilege at last, which helped him see the rest of his feelings with clearer eyes

so i'm really glad that something positive and warming was able to come out of it; something more meaningful than what revenge would have had. but while i'm so glad that natsume found some closure regarding his feelings, i still don't think that it means natsume should forgive ex-fine or ever antagonize them ever again... like i'm still here being like "i hope to god that altered got to win against fine-O LOL". i don't think OO made things "even", and i don't like that being the takeway from the event ...

but i think in the end, i'm not sure if i want natsume to get a cruel or violent "revenge", mostly because i think the feelings of his niisans mean a lot to him and his niisans do not wish for a devastating revenge and do not intend to inflict exfine & those associated with suffering.

tldr; i wish that he was able to perform eccentric party night alongside his niisans as the five eccentrics, but i still dont' know if going through it at that time would have been a good and safe idea for his sake

i like the idea of personal revenge though, where someone can get their "payback" in other ways; like for example, altered getting to show up fine-o in OO even if the audience doesn't truly understands what it represents. or for example, like rei said, prod at eichi's wallet if they ever need help with assets on a moment's notice LOL. the small hardships of atonement. there's been a lot of them here and there between the eccentrics and ex-fine, so i celebrate those as they come lol. do i still crave more? yes LOL