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

“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—”

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

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

Why were the Japanese soldiers in WW II so hesitant to surrender in battle?

“Exactly.”

“Tart!”

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

What is the most popular song that includes the word "you"? Are there any other songs that use "you" multiple times?

“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;

“Claire! Why are you still up?”

What do most wives fantasize about?

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

“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?”

“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—”

Why can't my adopted sister accept she is not part of my family because she isn't related? Why can't she stop calling my parents mum and dad?

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

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

“It’s not looking at you.”

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?

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

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

“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.”

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?

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?”

“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.”

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

Can you summarize season 1 of "The Acolyte"?

“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…”

“I need to do laundry.”

“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.”

Why do most atheists in debates with theists take Bible verses out of context much of the time? Are they lying maliciously or do they not understand theology enough to understand the meaning?

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

“Exactly.”

“Perv.”

Why do the Republican city officials at Springfield Ohio continue to deny that immigrants are eating pets to sabotage the Trump campaign, even though immigrant pet-eating is now widely believed to be true?

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

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?”

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

2 major cancer breakthroughs just dropped, and doctors are buzzing - Business Insider

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

Create a context between this character and other characters.

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.

What would you do if you found out that someone had broken into your home while you were sleeping?

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

“Nary a cute boy in sight.”

“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.”

How do great movie moments influence how people handle real-life moral dilemmas?

“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.”

“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.

“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.”

“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—”

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?”

“Cute girls?”

Do that and you can ground your characters quite quickly.

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

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

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

“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.”

“I’ll put the kettle on.”

“But they’re cold!”

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.

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

“You need some tea!”

Essentially, what you do is show the character:

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

“No way.”