The letter arrives on a Tuesday morning. Jack is at work, so Robby is home alone when he rips open the envelope and unfolds the letter inside.

He reads it three times, like he expects to find something new. It has to be a joke, or maybe it was sent to the wrong person. But it's his full name at the top of the letter, and the headed paper looks real.

As much as he would like to throw the letter in the trash and forget it even exists, he pushes the letter back into the envelope, folds it in half, and sticks it in the back pocket of his pants.

He says nothing to Jack as they do their usual handover and doesn't reveal anything as they share a brief kiss in the empty staff lounge. He wouldn't know what to say anyway; he's barely digested what the letter says himself, and there's a level of denial he hasn't shaken off yet.

The letter burns a hole in his pocket. Every time he helps move a patient onto a bed, pushes a wheelchair, or gets a blissful five minutes sat down at a desk, he feels it, he remembers the contents. And with it comes a short temper, snapping at Santos and Mohan and Whitaker in the space of an hour. Even Dana gets caught up in it, standing there with lips pressed tightly together as he lashes out at her.

When he's finished, she steps up to him, unafraid and under her breath says: "Whatever you got goin' on, get a handle on it."

He does his best to hold it in, but then he's just distracted, and he notices the way the interns and junior residents do their best to avoid him.

"What's up with him?" He hears Garcia mutter to Perlah after a patient dies in trauma one before they can get him up to the OR, and Robby curses loud enough for most of the ED to hear.

"No one knows, Dana's on the case though."

He soon finds out that Dana's version of 'being on the case' was to call Jack.

"What the hell are you doing here?" He asks when Jack strolls in. He looks tired, like he only got a couple of hours of sleep, which is likely.

Robby heads to the lounge for coffee, and Jack trails after him.

"Why do you think?" Jack replies, "Dana's worried about you, man."

"I'm fine," he insists.

"Talk to me, brother," Jack implores.

Robby's head spins sharply, "What did you just say?"

Jack frowns, confused by Robby's sudden reaction, "I just-

"Don't call me that," Robby growls. "We sleep together for Christ's sake."

"Oh, is that all we do?" Jack retorts.

Despite Robby's cutting words, Jack doesn't look offended. He feels guilty anyway. It's been months since they turned their strictly sex only arrangement into an actual relationship. He doesn't apologise; instead, he compartmentalises the guilt along with everything else and focuses on trying to make his coffee.