So I decided to be silly and take the Myers-Briggs test on behalf of my characters.
Myers-Briggs, if you're not familiar, rates people on four qualities and combines them to give you one of sixteen personality profiles. It measures Extroversion vs. Introversion (E vs. I), Sensing vs. Intuition (S vs. N), Thinking vs. Feeling (T vs. F), and Judging vs. Perceiving (J vs. P). It's not an exact science, obviously, and it relies on a person's self-reported beliefs about themselves, but it is nevertheless an interesting exercise for understanding characters!
Especially if, like me, your characters don't test out to be the same type as you.
I almost always test as INFJ. And even though most people suggest you should write what you know, I've always felt like my characters were very different people from me, and on this test, that was reflected.
(For the record, I took this test for my characters, and the abbreviated descriptions I'm offering here from that site have been altered slightly to fix typos.)
I did this test for four major protagonists: Ivy from The House That Ivy Built (and later Negative One), Delia from Bad Fairy, Cassie from Finding Mulligan, and Nick from Stupid Questions. First I'll show you their result, and then I'll give you a quick reflection on each.
Ivy's Result: ESTP (Extrovert/Sensing/Thinking/Perceiving)
In relationships you can be made to feel trapped by obligations and commitments. Your independent nature needs a great deal of latitude so you may roam as you need to. You will rebel against anyone who tries to control you. Unless you are with others that share your need for new and exciting experiences, those around you may find themselves sitting on the proverbial bench alone. You have the social skills and attitude to get along well with many types of people. You do not dwell on emotional issues. You rely on your charms to impress those you are attracted to. You're not one to shy away from a fight. You are materially generous, but may shy away from deep intimacy. You will bring excitement to any relationship you enter.
Is it true? This is pretty accurate for Ivy. She's definitely an extrovert--probably my only major character who actually seems to thrive on attention from others and feels particularly lonely when she doesn't get it--and she's definitely a free spirit. She's a go-go-go person who's always impatient with people who don't move as fast as she does, and she makes a ton of split-second decisions. She does have a tendency to sulk or brood sometimes, which this profile doesn't really cover, but other than that, I think it captures her well. The need for novelty, the rebellion against those who seek to control her, and the tendency to stand ground in a fight are all particularly appropriate.
Delia's Result: INTJ (Introvert/Intuitive/Thinking/Judging)
In relationships you are very loyal and prefer a traditional structure. You tend to only demonstrate your affections to those who are very close to you. You enjoy one-on-one relationships that are very intimate. You sometimes like extroverts, because they can take the "heaviness" out of your personality. You love the intellectual arena and the exchange of ideas. You are very sensitive to rejection but hide your emotional vulnerabilities well. While very loving, you can get so absorbed in your own projects that you neglect those around you.
Is it true? Sounds like the person who wrote this basically must have known her. Delia is a rather private and driven character who spends the entire first book focusing on her magickal studies with single-minded, nearly scary dedication, to the point that she sets achievement records all over the place and scares people's socks off. The bit about not being able to choose a direction is funny because she literally wants to master everything known along with a few unknown things too. She's very quiet, but formidable when challenged, and her best friend is more of an extrovert. Her mother complains about the "getting absorbed and neglecting your loved ones" bit.
Cassie's Result: INFP (Introvert/Intuitive/Feeling/Perceiving)
In relationships you are loyal and totally committed. You prefer a few deep relationships over a horde of acquaintances. Because you are somewhat reserved, you do best in one on one and small group situations. When you feel comfortable, you can be very entertaining and capricious. You are nurturing and supportive by nature. Your greatest social challenge is to balance your need to withdraw into your inner-world with your need to keep a strong connection with those you care for.
Is it true? It's hard to tell sometimes with Cassie, because in the story, she's really two people. I was trying to answer for the part of her that's actually Cassie, not the idealized version of her that lives in an alternate reality. (Dia is another story. She needs her own personality test, I think.) The part at the end there about withdrawing into an inner world is 100% spot-on and literal in her case. She travels to an alternate world in her dreams (where she is a different person), and it absolutely does affect her social life because it changes who she wants to be. She definitely has some creative bones in her body, and she spends a lot of this story looking for her love connection.
Nick's Result: ISTP (Introvert/Sensing/Thinking/Perceiving)
In relationships you are not one to have deep talks, but would rather let your actions speak for you. You display your love and care for others by doing practical things for them. You are not one to take on too many commitments or obligations--if any. You need your time alone and even though you are probably very loyal, this may cause conflict at times. You are not one to start fights, but you won't back away from one either.
Is it true? It's definitely true that people can't figure him out easily, and he's definitely paying attention to stuff that goes on around him, but the "preferring action to conversation" I'm not sure about. That said, in his relationship, she talks way more than he does, and he definitely gravitates toward practical solutions and wanting to provide for those he cares about. He thinks himself quite rational and gets really irritated and avoidant when he doesn't understand his feelings, which is interesting because he has a lot of those and doesn't want to deal with them.
And as a bonus, I saw this fun post on Tumblr where someone had figured out what Myers-Briggs types went with which Hogwarts houses, naming a primary and a secondary house. According to that chart, Ivy would be Gryffindor/Ravenclaw, Delia would be Ravenclaw/Slytherin, Cassie would be Hufflepuff/Gryffindor, and Nick would be Ravenclaw/Gryffindor. I kinda agree with those assessments too. Especially the one for Delia. Hahaha.
I think I might do some of my lesser protagonists and minor characters sometime too, but it's doubtful anyone wants to see me ramble about that. If anyone's read my stuff and wants to know a certain character, though, feel free to comment and bother me for the result. :)