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

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

“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.”

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

Humans Age Faster at 2 Specific Times in Their Life, Study Finds - ScienceAlert

“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.

Essentially, what you do is show the character:

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

What is the most offensive thing someone has ever asked you?

“Cute girls?”

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

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

Why did my ex of 2 years move on so fast after he left me? Why does he act so cold towards me, and as if I don't exist?

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

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

“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—”

My boyfriend always verbally abuse me and makes me cry. If I try to tell him how hurt I was, he says to me he loves me and can't hurt me but always abuse me. Why?

“Nary a cute boy in sight.”

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

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

My girlfriend told me that she wants to move in with me. I have my own apartment and I like my peace and quiet, but I also love her. We've been together for a year now. What should I do?

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

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

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?”

What do you think are the real reasons Matt Gaetz just withdrew his name for Attorney General in the upcoming Trump administration?

“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.”

“Claire! Why are you still up?”

“I’ll put the kettle on.”

Why do wokes use words like "homophobes" when they don't know what that means? Do they realize that no one is afraid of them?

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

“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—”

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

Why are white women dating more black guys than ever?

“You need some tea!”

Create a context between this character and other characters.

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.

If the world was flat, would it be possible to see Mount Everest if it was on the other side of the Earth on a clear sunny day?

“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.”

“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.”

“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.”

Does believing in God and Satan cause schizophrenia?

“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.”

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

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

Why hasn't Japan legalized same-sex marriage?

“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…”

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

“Perv.”

What does 'Whose flesh is like the flesh of donkeys’ mean (Ezekiel 23:20)?

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

“Tart!”

“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.”

If I get served by someone else's papers, am I legally required to inform the person that they got served, or the court that they served the wrong person?

“I need to do laundry.”

“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?”

“Claire, I—”

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

“It’s not looking at you.”

“Exactly.”

“No way.”

“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?”

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?”

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

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.

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

“Exactly.”

Do that and you can ground your characters quite quickly.

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

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

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?”

“But they’re cold!”