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—”

“Cute girls?”

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?”

Why is the French way to say please is "S'il te plaît" and not "Pour Favour" like Spanish and Portuguese "Per Favor" and Italian "Per Favore" in the Romance languages group?

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

“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.”

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

Why aren't F1 cars popular on the street?

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

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

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

What do you remember that 95% of us have forgotten?

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

“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?”

Why do people keep saying they have evidence and have presented it that proves you're wrong even though they have none and haven't presented anything? Furthermore, what do they think you're wrong about?

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

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

“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.”

What is the dirtiest city in India?

“Exactly.”

“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.”

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

How long can someone with narcissistic tendencies maintain a facade of fake love before their true self is revealed? Is there a specific trigger or amount of time that causes them to reveal their true nature?

“Exactly.”

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

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

Do handsome guys intimidate women or people in general?

“But they’re cold!”

“Nary a cute boy in sight.”

“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.”

What started the whole idea of femboys? What is the whole point of a femboy? Did a boy or a man just randomly start dressing or acting feminine or something?

“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.

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

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

How does a man look at you when he is in love?

“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?”

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

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

Why do so many people seem to hate Nickelback? They're competent and entertaining, and while they certainly aren't the absolute best music, they're still a fun listen.

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

“No way.”

“You need some tea!”

Why do people who aren't trans feel the need to put pronouns next to their name or picture? It seems so cringeworthy to me, to participate in that SJW paradigm of thought, like they are a spineless person who just goes along with the trends.

“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 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—”

Do that and you can ground your characters quite quickly.

Does the National Health Service (NHS) in the United Kingdom diagnose rare conditions? If so, does it provide treatment for them as well?

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

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

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.

King Charles III pays respects to Air India crash victims at his annual birthday parade - PBS

“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…”

“Claire, I—”

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

“I’ll put the kettle on.”

“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.”

“It’s not looking at you.”

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

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.

Create a context between this character and other characters.

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?”

“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.”

“Claire! Why are you still up?”

“I need to do laundry.”

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

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

Essentially, what you do is show the character:

“Perv.”

“Tart!”