Thing is, there are easier ways to do it. That's why it isn't an attractive choice.
Mami? We now have a huge bonus to diplo with her.
Madoka? We know her inside and out.
Kyoko? Buy her some pizza, ask her to help us hunt down some really damn big Witches and share the spoils reasonably. Training for Walpurgis, which has so many Seeds that she'd be set for ever if she got even a portion of its drop.
Sayaka? We're already making great inroads. She's probably dead this Loop, but next time, we don't bring her to that damn shop. Start off in need of help, befriend her, and ask for help in protecting people.
They take very little effort to actually get on our side, so long as we know what we're doing.
All of these take time, and none of them are perfect. Kyoko Sakura is a loose cannon who won't come to us so long as Mami Tomoe is still alive. Madoka could still contract.
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BleachDoctor insisted that I continue my thread in the public forum, despite the fact I have been scolded for dragging out threads before. I'll keep going here.
I said:
First, I'm going to point out that in Puella Magi Adfligo Systema I used moral arguments and was scolded for it.
Second, Homura Akemi is obsessed even pre-Homucifer. She was willing to kill Miki Sayaka and to hand Mitakihara to Kyoko Sakura despite knowing full well how many more people would die. Why would she likely hesitate at a bit of brainwashing for the greater good?
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BleachDoctor said:
From what I hear, they were very bad arguments, but I haven't seen them myself, so whatever.
Homura was willing to kill Sayaka because she knew that Sayaka was on a downward spiral from which there was no return. It made logical sense to kill Sayaka before she could cause more damage on her way to Witch-hood. As for handing over Mitakihara to Kyouko, what, who else would she hand it to? Sayaka? Yeah right, that would end well. Better a single protector than none at all.
As for brainwashing, this just isn't a very good idea. We're trying to play Homura to the best of our abilities, and while it would be easy to go full murderface and just blast our way through timelines, caring not for the wellbeing or personal freedoms of others, we need to make sure that the world is one we want to live in afterwards.
Now, if you want to continue this discussion, feel free to do so in the main thread. If you think your argument is that good, then you should have no problem putting it up for public critique.
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I'll get back to it from here. Mods, if you're listening please don't penalise me for trying to being accomodating.