Thanos regards Grim expectantly.

"I need to know who sent you those messages." He gives her room to provide a name on the off-chance that the conspirator identified themselves in previous correspondence. When she doesn't offer up anything of the kind, he presses onward. "Which means we need transcripts of all prior correspondence--preferably the original articles, but a recitation will suffice if the originals aren't available."

The girl has a highly above average memory for her species. He trusts she can recall the wording well enough if she needs to, and he doubts she'll try obstructing things anything further.

All the same, when he releases her shoulder he watches her very closely.

She recites the second note word for word, tone almost mechanical.

Thanos listens. He does not seem to like what he hears. 

“It was one of us, then.” Proxima speaks up after the post-script. “A stowaway or a traitor Chitauri would not need to ‘lie to her face’ if Grim spoke up publicly about their correspondence.”

“One of my children, a traitor...” Thanos does not want to accept this notion, but the evidence speaks clearly.

”Grim. Who do you suspect?”

She startles a little. "I- me? I- wouldn't know enough to even guess."

"That seems unlikely. You've had weeks to get to know us all, and the traitor speaks to you in such a familiar fashion... you'd have to be quite dense to not at least have a guess."

Proxima paces around behind Grim, gesturing irritably at empty air.

"As for me? I'm reasonably confident it isn't Corvus. That's why I tasked him with locking down the residential wing." She pauses momentarily, trying to put into words her reasoning for trusting her eldest brother. "He's... the least sentimental, out of the lot of us."

"From what I've observed, you're all loyal, and not idiots. The only person I haven't really interacted with is Nebula, and I'd hardly pin an accusation on someone I haven't interacted with."

"Right. Nebula. I keep forgetting she exists."

Pause.

"In hindsight, it's obviously her."

"I'll need to speak to everyone, of course. Starting with Nebula."

In hindsight, it's obviously her.

Thanos dispatches an envoy and, a couple minutes later, a squad of Chitauri enter the room.

Thanos' oft-forgotten middle daughter stands sullenly amidst them.

"What?"

-This was not, in fact, what Grim had intended. But she's not one to question good fortune. She remains quiet and impassive, forcing the shadows that want to wreath her form away.

He gives her a chance to speak up freely before making inquiries.

"Nebula. You know how I feel about dishonesty. If you've been keeping something from me? Disclosing it now would be bad, but disclosing it later would be worse."

If she is the one who's been sending those letters, then she knows full well why she's been called up here.

Nebula looks nervous.

Pretty understandable, given the stern titan speaking to her.

"Would someone please tell me what's going on?"

Proxima relates the story of finding a seditious missive in Grim's quarters.

"What? You think I'd do something like that?"

Nebula glances from Proxima, to Thanos, to Grim.

"Why?"

"I don't know you well enough to say either way."

Thanos towers thoughtfully over his three daughters, listening intently and saying nothing.

He takes no pleasure in any of this.

Proxima does take quite a bit of pleasure in her sisters' discomfort.

"We called you in first, Nebula, because you were the only one of us that Grim couldn't confirm as being loyal and non-idiotic."

Grim shrugs, unapologetic, but makes no excuse - she didn't have enough data to make that assessment.

"Well fuck you too, then."

Nebula's expression defaults to pissed-off-looking even under less adversarial circumstances. This baseline only becomes more pronounced as the present conversation draws out.

She swings around to face Proxima.

"And why were you even snooping around the nursery anyway? Needed to play with your dolls again?"

"Nebula. This is serious."

Pause.

"Do you have anything to say in your own defense?"