How I know her: Mutual friends in school
Health care stuff. Biology. Pathogens. Curing diseases and such -- not through being a doctor, but through lab work. She's very dedicated to the cause. Don't even get her started on people who refuse to give their children vaccinations, because she WILL rant at you about it, for an hour.
I'd also say she's interested in any institutional flaw, in any institution. Especially the government, the health care system, and education (be it in the home or in schools).
Hilarious, self-deprecating, self-referentially awkward sense of humor. Very loyal, very caring. Quick to help in any situation/always wanting to be helpful. Romantic in a 12-year-old girl kind of way, which is pretty cute. Endearing tendency to ramble without noticing that people aren't interested.
Very very judgmental, irrational, holds grudges for a very long time even after recognizing that she should never have held the grudge in the first place. Has issues communicating her feelings that may or may not be type-related, but gets angry at people for not being able to read her mind. (Will compare them with her INFJ roommate, who pretty much CAN read her mind, so the comparison is unreasonable.) Has unusually authoritarian moral tendencies; will often say things like "I would never let my children do X", or "If I were President, I would make X illegal", with X being something that most people would either not find terribly offensive, or would believe that individuals have the right to choose to participate in or not participate in. (I'm leaning SFJ or NFP because of this, but I'm unsure about Fi vs. Fe.)
Fluffy side note:
She thinks that if she were a villain, she would be Light Yagami from "Death Note" -- and although I mostly see that as being accurate, she would probably be way too excited about the whole thing, and would instead declare her identity, her goals, etc, to the media, as soon as she got the notebook. And she would probably be pretty long-winded about it all. So... my friend and I decided she would be Mojo Jojo from "The Powerpuff Girls" instead
She's fairly work-hard/play-hard. The sort of person who loves putting a lot of stuff on her plate, complaining about how stressed she is, and spending 90% of her time holed up in her room/in lab doing work -- but at the same time, the sort of person who bumps and grinds with EVERYONE at the club and leaves with several phone numbers and business cards. (This is a major reason for my friends and I deciding that she's a counterphobic 6.) Quick to pick people up and then drop them, in romantic relationships, but not nearly so quick with friendships.
Personality typing history:
Tested as ENTJ, but nearly 50/50 on every single letter, and she doesn't even remotely seem ENTJ to me; I'm almost certain of ExFx.
She hasn't even heard of the Enneagram, let alone taken it, but another friend and I are 100% sure that she's a 6, and I'm guessing her tritype is 6wX-1w2-XwX. (Probably 6w5, though she's a bit of a chameleon in that regard. Could just have balanced wings?)