When writing a novel, how can a character be developed well, but QUICKLY?

“But they’re cold!”

Here’s how we presented the character Claire when she was introduced, which the agent particularly singled out:

“Nary a cute boy in sight.”

Why is squid ink safe to eat, while skunk spray is not? What makes the two liquids different from each other?

“You don’t need a cat. You can’t take care of a cat. You can’t take care of a ficus.” Claire flopped on the other side of the sofa and wriggled her feet beneath May.

Create a context between this character and other characters.

“I need to do laundry.”

Will my 9 year old face more difficulties than most girls her age if she’s an early bloomer? My daughter already needs regular B cup bras. The doctor says that my daughter will be even more developed by 11-12 years of age.

“No, about the cat. You don’t need a cat. You remember what happened to your spider plant, right?”

“They are! He broke the rules of the boarding house by petting this character while she was in cat form, so they invoke the ancient rules of single combat via ping-pong, and—”

“I’m glad my sex life is so entertaining.”

What kind of person makes you think "how come there are people like that"?

“I’ll put the kettle on.”

“Thanks. You’re looking pretty ratty yourself. Have you been in that bathrobe all day?”

Claire sat back down, legs tucked elegantly beneath her. “You are looking a bit sloppy,” she said, inspecting May through narrowed eyes.

Why is my crush beautiful to me but not to others?

“About wearing more clothes? How am I supposed to catch any fish if I don’t show off the bait?”

“No way.”

“Perv.”

Which Shakespeare words have completely changed meaning in modern English?

“It’s a cat. All cats are weird.” May sipped from her mug, inhaling the warmth. She closed her eyes. The room spun. She opened them again. “Ugh. I think I drank too much.”

“I don’t know. Partying. Going to a pub. Anything besides sitting on the couch reading…” She squinted. “What the hell are you reading?”

“Fine.” May collapsed into the warm spot Claire had just vacated.

Would you join a gym or workout at home and why?

“Exactly.”

May pushed Claire’s feet away. Claire rose to peer out the window. “Huh. It’s still there.”

Essentially, what you do is show the character:

Why does my cat get anxious during loud noises like thunderstorms or firework displays? Is this a common behavior for cats, and is there a way to help them cope with it?

Claire, one of May’s three flatmates, former university roommate, and best friend in all the world, shrugged expansively. “It’s a Saturday night. What else would I be doing?”

“Number one, it’s not porn, it’s ecchi, and number two, why would I waste a perfectly good Saturday doing anything else?” Claire pulled at her tea and sighed. “The only thing that could make this day better is if you'd come home with some cute boy, so that after you kicked him out tomorrow I could live vicariously through you.”

“Nope, I mean a cat followed me home. A black cat, to be exact. All the way from the club. Probably still out there, for all I know.”

Why do women have sex with dogs?

“Well, maybe if you’d wear more clothes, they wouldn’t feel so cold. Hussy!”

“Exactly.”

“Cute girls?”

Do straight guys like to have sex with men when they smoke meth?

“Damn straight. So get to it! This time next week, I want to hear some moans coming through that wall.”

Doing something they enjoy, that expresses their personality, and that is in some way unusual or noteworthy;

“Hang on, are they playing ping-pong?”

Why do flat Earthers still exist even though it is scientifically proven that the Earth is spherical?

“May! You’re home late! Early, I mean. Well, I mean, it’s early in the morning, but you’re home before I expected. Er, after. Before?”

“I’m serious!” Claire said. “It’s staring straight at me.” She let the curtain fall. “Weird.”

In the kitchen, Claire set out a battered pair of mugs: May’s black, with “PEBKAC: Problem Exists Between Keyboard and Chair” in white letters; Claire’s white, with “This must be Thursday. I never could get the hang of Thursdays” in dark blue. She carried both mugs into the living room. “A moggie followed you home? Is this some weird Internet slang I’m not current on?”

Long-term study ties midlife vascular health to later dementia risk - Medical Xpress

“Tart!”

“Claire! Why are you still up?”

May yelped. “Hey! Your feet are cold!”

How many women have accidentally pooped their pants and became turned on afterwards?

“Well, maybe if you didn’t spend all day reading—” May prodded the book with its garishly-coloured cover with her foot. “Bizarre comic book porn…”

“You know what? Never mind,” May said. “I am way, way too drunk to be having this conversation.”

“Claire, I—”

To a flat Earther, what's wrong with the idea that gravity is simply a force inherent to space which operates only in one dimension? Why do they go further and try to deny gravity rather than just saying it's different than physicists claim?

“I know! That’s why I’m putting them under you!”

“None of those either. Look upon the wasteland that is my sex life, and see that it is barren. Naught but a moggie followed me home.”

After Eunice and I finished London Under Veil, I entered the first chapter in a contest at a convention where you could submit something and have it critiqued by a professional book agent.

“From the look of you, if you try to sleep now, you’ll spend the next three hours hanging onto your bed trying to stop the world spinning. Since you’re not going to sleep anyway, you might as well keep me company.”

Do that and you can ground your characters quite quickly.

May studied the black and white comic panels. “Oh, my. She looks…anatomically implausible. What is she doing to that poor man? Wait, are those cat ears?”

“Yuuna and the Haunted Hot Springs!” Claire turned the book around.

“I try not to, but thank you for reminding me. I know I don’t need a cat. I don’t want a cat. What would I do with a cat?”

Engaging in conversation that also shows something about their intelligence, personality, wit (or lack thereof); and

“Yep!” Claire chirped. “There’s this schoolboy, see, and he’s homeless, so he lives in this boarding house that used to be a hot springs bathhouse, which is cheap because it’s haunted, so he decides—”

“So you didn’t meet any cute boys at the club tonight?” Claire called as she bustled about the small kitchen.

The agent had only one bad thing to say (the synopsis was crap; writing synopses is hard!), but praised the characterization and particularly how well we introduced a character’s personality quickly.

“It’s not looking at you.”

“You need some tea!”

“I’m just a fan of your catch and release program.”

They both burst out laughing. “I’m right, though,” Claire went on.

“Why is that always your first suggestion? I do not need some tea. It’s three o’clock in the morning! If I have tea, I’ll never get to sleep.”

“Yes way. It’s washing itself under the street light. Uh-oh, I think it spotted me. It knows I’m watching it. I swear it’s looking at me.”