Hehe I knew someone would start talking after Episode 15 aired
The next few eps are like the calm after the storm. Ep 14 and 15 really rocked my socks. I loved it.
Ok, I’ll try to explain my interpretions, and the significances and such. So, SPOILERS BELOW, PEOPLE!!
The old witch, Methuselah, was a 400 year old witch from the Salem Witch Trials. She was “destined” if you will, to act as sort of a savior or seer, overseeing all the witchcraft activity of her time and the times to come. Because of her rank (which I believe was uncontrollable, she was just a very powerful witch, and thus was granted eternal life), she got to live forever. As she lived on in old age, she gained a lot of knowledge pertaining to her people, their fate, their abilities, etc. This knowledge gave her the ability to control any witches power-you see this, when the electrical witch guy (I forget his name) went crazy when his power awoke-and she “shut” them off. I believe she intentionally awoke his power, in hopes of drawing STN-J closer to her. What she really wanted was Robin. She’s the one who indirectly hacked the STN-J terminals, as well.
So when Robin was drawn to her, Methuselah explained her position. She told Robin of her heritage, and the fact that every witch seems to be reborn, in a sense. At least their essence does. This is why she claims Robin was present at the burning times. On a side note, Pagan religions, such as Wicca, believes they get reincarnated after each life, and many seriously feel they were killed in the Salem Witch Trials.
She also explained that witches were decendants of a god called Saturn or Satyr, depending on what sub/dub you watch. This may or may not tie in with Christian tales-Saturn was said to “fall” from heaven because of witch spawn; he created the race, which flourished and prospered. The humans were slaves, and extremely jealous of the witches abilities, and there came a time when mutation occured within the witch genes and many of them could not pass their abilities on. This caused the downfall of the witch raced; the humans conquered them, and only rarely did the witch gene surface again. One who was born with it was obviously an outcast, or some type of filth, as you’ve probably noticed from watching the show. Because witches are heavily outnumbered, many of them are killed because of the sudden awakening of their abilties, which more often than not trigger violent personalities, or if that doesn’t happen, the witch uses it to harm others, for whatever reasons. Most who get caught using thier abilities have no idea whatsoever what’s happening to them. This is basically Methuselah’s story, I just elaborated on it, to explain the history more. After she reveals all this to Robin, she basically claims that witches and craftusers are one and the same, because, technically, they are, and no matter what they use their abilities for, they will always be witches, which Robin vehemently denies.
After this, Methuselah commits suicide and controls Robin’s fire craft to burn her to death, because she was immortal. She could never die; nothing could kill her, and she wanted her observation of witches suffering to end. The only way for her to pass on was to destroy her soul, which fire did. That’s why she needed Robin. To control her craft; all she wanted to do was die.
It’s been awhile since I saw the Inquisitor ep, so bear with me. He was the guy that tested Robin’s worthiness to become a hunter. That’s what Inquisitors do; they pick out witches and test them with orbo to see how they think and how they will react. If they pass the test, they are no longer deemed as witches, but craftusers, and end up working for Solomon and it’s many branches, such as STN-J. I think that ep was to explain how Robin came to STN-J in the first place, and how that whole hunter process worked. We also assume Amon and Karasuma went through the same test, because well…because I wont say anymore 
But anyways, I’m pleased to see the reaction it’s getting here in RPGC. I didn’t care much for the dub, but I still need to watch more eps to make any final judgements.