"I know how my comms work. Sound waves converted to electrical signals converted back to sound.'

Fitz looked suitably impressed. Jemma smiled.

'Don't look at me like that. I did pass high school physics,' May cast them both a withering gaze.

'Yes, that's an excellent foundation,' said Jemma. 'But today we're going to dig a little deeper.'

They were sitting in a corner of the lab, surrounded by a timeline of communications technology, from heavy Vietanam War-era radios the size of a large backpack to tiny microchips held in vials of pale blue fluid. Some of the items seemed vaguely familiar to May; maybe she'd come across them in training.

Fitz was leaning against a whiteboard, twirling a marker in his hand. There were already several rough diagrams, of electromagnetic radiation and cryptography schematics.

'You know Coulson's the history buff, not me.'

Fitz nodded happily. 'Yeah. He lent us half this stuff.'

Now that he mentioned it, May realised that many of the relics looked familiar because she had seen them before in Coulson's office. On display behind glass. May briefly wondered what Fitz had offered him in exchange for this privilege. Maybe he'd finally agreed to add an instant coffee maker to Coulson's arm.

'So anyway,' Jemma said. 'We're going to be explaining the nitty gritty of the communications system. Encryption software, channel mixing, DNA encoding, how we deal with interference, voice-activated modulation...all the things.'

Jemma's list of syllabus content turned out to be an understatement. May spent the day frantically trying to keep up with the two of them as they explained every aspect of the communications system. They spent a great deal of time going through the encryption system, the way the communications were scrambled and then decoded to prevent any messages from being intercepted. They also discussed the clarity of the signals, how the software was designed to minimise background noise. There was even software to detect location and tone of voice, so that when agents in multiple locations were on the same comms channel, HQ could easily hear the most important messages. Jemma even went into an entire lecture on anatomy and molecular biology, to explain how the latest comms were implanted for optimal sound quality and encoded to each agent's DNA so that they could not be stolen and compromised.

By three o'clock in the afternoon, May's brain was thoroughly fried, although she had to admit - not for the first time this week - that these two scientists were pretty amazing teachers. She'd learnt more from them in a day than from her high school biology teacher in four years.

But she was pretty ready for a break and a gym session, so she had to suppress an inward groan when Fitz proudly declared that they'd prepared a training exercise for her.

'So Fitz and I are going to opposite ends of the base and we're going to have a conversation over this newest comms model,' Jemma explained. 'It's so new that it hasn't been released to field agents yet.'

'We're not going to tell you the frequencies or encryption devices,' Fitz chimed in. 'But you'll have access to all this lab equipment. And you're going to hack into our comms.'

May stared at them for a long moment. Then, she said simply. 'Okay.'

Fitzsimmons exchanged a grin and left the lab, heading down opposite ends of the corridor. May took a seat at Fitz's computer and began to type.

'How long do you think it'll take her to hack in, Fitz?' Jemma asked across the comms. She had found a corner of the locker room to hang out in.

Fitz considered the question. 'She'll have to scan and decrypt across multiple frequencies but most of that is automated, so...I reckon an hour or so.'

'Yeah, sounds about right.'

There was a period of silence, broken only by soft groans as Fitz shuffled around, trying to get comfortable on the floor in the hangar.

Finally, Jemma had had enough. 'Honestly, Fitz, just pick somewhere more comfortable to sit. Go to the lounge or something.'

Fitz shook his head, even though Jemma couldn't see it. 'No, no, I like the hangar. Reminds me of the old days. The Bus used to be parked on here.'

Fitz heard Jemma sigh fondly. 'Oh, the Bus days! We were such babies back then. Us and Daisy - Skye, actually - and May and Coulson and-'

'-and Ward,' Fitz spat out. But then his tone softened, 'Ah well, we had good times despite Ward.'

'Yes, remember the shaving cream incident?' Jemma giggled, and laughed even louder when she heard Fitz groan.

'To this day I haven't figured out who did it!' Fitz cried in indignation. 'Do you swear it wasn't you?'

'For the last time, Fitz, it wasn't me!' Jemma was still laughing; Fitz could hear it in her voice.

'Well, who was it then? Because everyone denies it. I'm thinking Daisy, but she's never admitted it.'

There was silence on the other end, and Fitz regretted bringing up Daisy. Jemma had taken her departure quite hard.

'I miss her,' Jemma said finally.

Fitz sighed. 'Yeah, I know, Jemma. Me too.'

'I think May took it quite hard as well,' Jemma said sadly. 'She sees herself in Daisy. Strong, smart, misunderstood. Running away from the world because she thinks destruction follows in her wake.'

They hadn't really talked about this before, and Fitz marvelled once again at Jemma's wisdom as he listened quietly.

'She'll come back, Jemma,' he said gently. 'We're her family. She's hurting right now, but she'll come back. I believe it. We have to believe it.'

'I know, Fitz,' Jemma replied, and Fitz was pleased to hear a small smile in her voice.

Their phones buzzed simultaneously.

I'm in. You're talking about Daisy. - May

'That was quick!' Jemma said, impressed, and a little concerned that May had heard them talking about her.

'We're coming back to the lab, May, see you in a bit,' said Fitz, now knowing that May could hear them.

Back in the lab, they praised May on passing the test with flying colours. May didn't seemed bothered by the contents of their earlier conversation

'So class dismissed?' she enquired.

'Class dismissed.' Fitz confirmed.

'And May - about what we were talking about -' Jemma started, but May waved a hand dismissively.

'It's okay, Jemma. We all miss Daisy and you didn't say anything that wasn't true.'

'But I-'

'Oh, and Fitz,' May cut Jemma off, and both of them were shocked to see a sly grin spread across her face as she turned to Fitz. 'It was me. Your bunk code was MONKEY.'

May turned on her heel and strolled out of the lab. Fitz's jaw dropped open.

'No. May- she-,' he stammered in disbelief. 'Surely not.'

Jemma took one look at his wide-eyed, slack-jawed expression and dissolved into uncontrollable laughter.