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Obviously that's just Kyubey molesting her to turn her into a magical girl, like he did to Sayaka. Or should I say like she did.

No really, that is a bit of a mystery.

 slight speculation that still seems pretty likely

The grief seeds are tainted soul gems of magic girls. When the gem gets completely black, they probably turn into witches, but it probably takes a lot of sin for it to become that black. Someone took this speculation and made a really nice chart of it last week:

 Spoiler

Well, I read lots of mystery stuff, and those are all about picking up on small clues and trying to find out what's going on. When watching this and talking about it online with others that are doing this as well, we pretty much help each other by picking up on things the others didn't get, or building up on each others ideas. I honestly wouldn't have been able to crack the runes that appear in the series (and no, they haven't been abandoned, someone posted that in EP7's witch fight the runes were still there, but they were kind of blended into the background). Stuff like that can only really be done with cooperation, I don't really think it's something a single person can do quickly.

And of course, lot all the speculations are correct, but when you create a lot of plausible ones, one of them is bound to be at least partially correct.

So, going by your chart there...

 Spoiler

Kyubey is just the "angel from the heavens" kind of character, in that he is just disconnected from the world of humans. This would kind of make sense with the wishes being seen as "miracles" here and there, rather than just wishes. When I think of a wish, I think of something I need that I could eventually get myself, but when I think of miracles, its something I will almost never achieve on my own, or in any realistic realm. Given that, Kyubey really could be good, but is unable to see what his actions do wrong for the girls, as he is disconnected from humans.

Now, I say this, because why would Satan, who walks once a year collecting grief seeds, need Kyubey to collect them? It would just be redundant. I also see Madoka as having great potential because her soul gem would be able to last longest in fights, meaning she would not have to cleanse her gem as often as Sayaka or Homura would.

Freezing - 7 - Awesome fighting, but they really are ratcheting up the power levels fast with each episode. Sad story for why Satella doesnt like being touched.