Four years ago, when Peter left his birthday cards scattered over the kitchen table, Elizabeth picked one up on the way to the refrigerator. She'd read the message inside and smiled, because if she was going to share custody of her husband with his job, it was good to know they appreciated him. And they did.

One card turned into another; she'd laughed at some of the covers and stared uncomprehendingly at some of the messages. She'd decided "Mr Smith-Jones-Smith" was something she probably didn't need – or want - to know about.

The last card she picked up had confused her: a cupcake on the front but no message inside. When Peter had wandered in fixing his tie, she'd stood between him and the coffee pot and held the card up. "Who sent this one?"

He'd plucked it from her hand and grinned. "Caffrey."

There were a number of questions she could have asked, but honestly, at this point they were three years in and she was pretty sure she knew the answers to most of them. She'd gone with the most intriguing: "How do you know?"

"He signed it. NC, see?" His fingertip had brushed what she'd thought was a printer's error – a tiny smudge in the corner. Even holding it up to her nose, she hadn't been able to see anything more. Then Peter had fished a loupe out of his jacket pocket and, when she held it to her eye, she had just been able to make out the tiny initials.

"Well he's got a future writing on rice when he gets out," she'd said.

Peter had kissed her and then there had been a call.

(She doesn't remember what the case was now – they blur after a while - but she does remember that she didn't see him for three nights.)

-o-

Three years ago, when Elizabeth had wandered into the office to turn off the lamp in the corner, she had seen the birthday cards had made it to his desk this time. She'd looked for the odd one out and it had been pretty easy to find: it was the only one from a 17th century Dutch painter.

Rembrandt had even been kind enough to sign it.

When Peter had come in a few hours later, he'd swooped in to kiss her cheek and then nodded when she held the card up. "That's good work. You see the brush strokes there? And the signature … " After a moment he had caught his enthusiasm, coughed and said, "So I should probably tell the Governor to monitor the materials Caffrey gets his hands on more closely."

(As far as Elizabeth knows, he never did.)

She'd said, "Are you going to send him a card?"

"It wouldn't be appropriate. Anyway, he's just yanking my chain."

His eyes had darted up to hers and she'd remembered how good he'd always been at asking her questions without actually her asking questions - at looking for confirmation without looking like he needed it.

She hadn't mentioned the two blank cards she'd seen in his desk drawer (she still hasn't, and there's four now). "That's a lot of work for someone just yanking your chain," she'd pointed out.

"Well, it's not like he doesn't have the time." Peter closed the subject. For that year.

She'd smiled brightly and said, "You want your cake? I think Satchmo left some…"

-o-

Two years ago, Peter was in Washington, so she opened his cards for him and left them around the remains of dinner.

He'd come home some time after 3am ("of course I didn't cook, who do you think you're talking to?") and she'd shoved the card into his hands before he could do more than loosen his tie.

It was in a vintage photograph style, with an old car on the front and completely bare on the inside. "Where did he sign it this time?"

"You opened my cards? What if there'd been something from my mistress in there?" He dug in his kit and extracted a blocky UV lamp.

She'd laughed (she'd coped with Peter's other woman for six years by now). "I'd have warned her not to make dinner and left you for the Redmond's pool boy."

"The Redmonds don't have a pool - huh."

"No UV?"

Peter had tucked the lamp away and brought up a mini heat wand in its place. He'd waved it slowly back and forth under the card until a scrawled 'Happy birthday' began to appear. It had looked like it was singed and she'd wondered if it would burn.

She'd hung over his shoulder anyway and watched with fascination as the words appeared. "How did he do that?"

"Cola, probably. Could be milk. Lemon juice if he has kitchen access. Hell, soap water. There are other ways but," Peter's eyes had flickered to her and he'd coughed, "they aren't likely."

Yeah, she wasn't going to touch that one.

-o-

One year ago, Elizabeth sorted through her birthday cards and was less surprised than she thought she'd be to find one from Da Vinci.

(There's another blank card in the desk drawer).