Title: We Need to Talk About Morgause 
Rating: T+ (this part)
Character/s: Merlin, Arthur, Morgana, George
Summary: Arthur finally makes his move. Morgana makes a big mistake. And Merlin, ultimately, has to make a choice – but will it be Arthur? The final instalment of the We Need to Talk series.
[ Prequel | Part 1 | Part 2 | Part 3 | Part 4 | AO3 ]
Warnings: None (this part).
Word Count: 1100 words.
Prompt: 342 Letter to Santa
Author's Notes: n/a.
“The thing is,” Morgana says, taking a deep breath. “Morgause is our sister. Well. Half-sister. Apparently, Uther got his girlfriend pregnant while they were at university, and she was the result.”
“Our sister!?” Arthur drops the paperweight he’s been holding and stares at her. “You’ve been sleeping with our sister?”
“What? No, gross, Arthur.” Morgana wrinkles her nose. “We’ve been spending time together, that’s all. You know, hanging out. Sisterly bonding?” She looks from Arthur to Merlin and back again, then seems to decide that Merlin is the more rational of the two and turns towards him. “She reached out to me a few months ago saying she wanted to meet me, and, well, I couldn’t see any reason to refuse. She asked a lot of questions—about Arthur, Uther, what we do at work, that kind of thing—but I genuinely thought she just wanted to get to know me. It never occurred to me that she might have an ulterior motive.”
She sighs, running a hand through her hair, and Merlin feels a twinge of sympathy. For all the trouble she’s caused, Merlin is pretty sure Morgana didn’t do it on purpose, and he knows only too well what it feels like to be deceived by someone you love.
“I didn’t even realise she was involved at first,” Morgana goes on. “Of course, I knew you hadn’t done it, Merlin—the day you betray Arthur is the day piglets get their wings. But if what you say is true, then Morgause is the only other person who could have passed along that information. She must be the mole.”
“But—why?” Picking up the paperweight again, Arthur begins to pace, tossing it from one hand to the other as he walks. “She doesn’t even work for Essetir. Why would she want to help them?”
“Revenge,” Morgana says simply. “She’s—she’s really angry at Father. She says he was the one who insisted on giving her up for adoption.”
“How would I know? All I know is what she’s told me.” Morgana shakes her head. “She must have gotten Merlin’s details from my laptop at some point and used them to set him up.” The corners of her lips turn down. “I’m sorry, Merlin. I should never have trusted her.”
“It’s not your fault.” Merlin glances over at Arthur. He has stopped moving now and is leaning against one of Morgana’s bookshelves, scowling at the floor, but Merlin can tell he’s listening. “We’ve all trusted someone we shouldn’t at one point or another. And she’s your sister—you couldn’t have known she’d pull something like this.”
“Still…” Morgana is studying Arthur too, her mouth set in an unhappy line. “She’s been getting even pushier lately, especially since that Smith woman came by, but I didn’t think—” She cuts herself off. “I was stupid. I should have told you about her ages ago, but she said not to.”
“She knew you trusted her, and she took advantage,” Arthur says, his voice quiet. “That’s on her, not you.”
He sounds like he means it, and Merlin doesn’t have to ask to know that he’s thinking about Sophia, and maybe about Edwin, too. Morgana’s expression softens.
“No. Merlin was right,” Arthur says firmly, straightening up. “And you know how rarely I say that. We’ve all trusted someone we shouldn’t have, and it sucks. The question now is what we’re going to do about it. We can’t let Morgause get away with this.”
Morgana starts to speak again, then stops and turns back to her computer, entering a few rapid keystrokes to bring something up on her screen. “I think I know how we can stop her, actually.”
“Really? How?” Arthur peers over her shoulder, frowning as he tries to make sense of what he’s seeing. Merlin hides a smile behind his hand. Arthur never was very good with computers. “What is this, anyway?”
“It's a letter to Santa,” Morgana deadpans, sounding a lot more like her usual self. “What do you think it is?” She tosses her hair back and looks at him, her trademark smirk once more firmly in place. “Morgause may have stolen information from us, but I’ve also learned a thing or two about her. When she first surfaced, I had George run a background check to make sure she was who she said she was. Maybe we can use that to track her down and clear Merlin’s name.”
Arthur just blinks at her, apparently too surprised to speak, but Merlin leans forward in his seat.
“Morgana, you’re brilliant,” he says sincerely. “Where do we start?”
By the time they leave Morgana’s office, it’s already well into the regular workday, but for once Arthur seems to have other things on his mind.
“Come on,” he says, tugging Merlin away from his desk and towards the elevator. “While Morgana’s doing her part, there are asome people I want you to meet.”
“Okay.” Merlin trails after him, watching Arthur closely out of the corner of his eye. It’s not every day you find out that you have a secret half-sibling stashed away somewhere, let alone that she’s been selling family secrets to your company's rivals behind your back. This is the stuff of soap operas, and knowing Arthur, Merlin is willing to bet he’s not half as cool about the whole thing as he’s trying to pretend.
“So,” he says finally, nudging Arthur in the ribs as the two of them stand waiting for the lift. “Your dad sure got around, huh.”
“Shut up, Merlin,” Arthur replies testily, rolling his eyes. “I don’t want to talk about my father’s sex life right now.”
“Do you ever want to talk about your father’s sex life?” Merlin asks. Arthur shoves him sideways in response, and Merlin staggers, grinning. “Prat.”
“Still not a word, Merlin,” Arthur reminds him, but he’s smiling, and best of all he’s touching Merlin again, both things that Merlin has been forced to do without for far too long. “You really need to work on your vocabulary.”
“And you need to work on your people skills,” Merlin says. “Didn’t you notice your assistant has been trying to get your attention for the past five minutes?”
“Oh, Christ.” Arthur groans, dragging Merlin after him as the elevator dings. “Hurry up, or he’ll start haranguing me about my filing system.”
Obediently, Merlin hits the ‘door close’ button, and the next moment he has the pleasure of watching Mr Efficient’s well-organised grimace as the lift shuts neatly in his face.
Merlin: 1. Imposter: 0.