Radiation: A stream of particles or electromagnetic waves emitted by the atoms and molecules of a radioactive substance as a result of nuclear decay.

Its only two days until he's able to go home after Mission City, but it's two weeks beyond that until Bumblebee is repaired enough to roll back into his driveway. Sam pounds down the stairs despite it being three-AM, bursts out the back door before his father can even start yelling, and dives into the open drivers door, grinning his head off even though Bumblebee's playing 'So Happy Together'. "So, you're really staying?" Sam asks the stereo.

The radio cuts briefly to static. "Yes, Sam," Bumblebee says, and his voice is kind of weird and harsh but really awesome, too. "I'm staying."

Chronic dose: A dose received over a long period of time.

"Sam? You okay?"

Sam looks up at Mikaela and smiles, but she can still see the bags under his eyes. "I'm fine," he says. "Just a little tired."

"You look exhausted," she says, worrying at the inside of her lip.

"Maybe I caught a bug or something," Sam shrugs. "I've been getting plenty of sleep."

"Maybe you should get more," the girl suggests. "You look... you don't look so good."

Sam waves a dismissive hand. "Nah, I'm fine," he repeats. "Me and Bee are going up-state this weekend, come with?"

Dose: Amount of radiation received based on biological impact.

He's too tired, his skin's too flushed, his stomach's too queasy. "Bumblebee," Sam says. "I think I'm sick."

Bumblebee's processors churn at the thought of his friend in discomfort. "Do you want to go see a medic, Sam?"

Somatic effect: Person receiving radiation shows effects.

"Radiation sickness?" Sam repeats. He looks at Ratchet, eyes wide, bright with fear. "You think it's from the Allspark?"

Ratchet looks grim, terribly grim, optics settling on Bumblebee, on the way the scout held his human before him, forming a chair of his hands and his chest for Sam, close to his Spark. "No, Sam," he says heavily. "I don't think it's from the Allspark at all."

Deterministic effects: Somatic effect of radiation due to extensive cell death or dysfunction.

The sunset view at the overlook is still amazing. "I shouldn't be here, Sam."

The young man shrugs a shoulder. "A few more gammas won't hurt me," he says. He doesn't look at the robot. "So, what're you guys going to do?"

Bumblebee can't look at the human, either. "We're going back to the Ark," he says softly. "We'll remain in orbit, to watch for Decepticon activity. Optimus decided that it would be the wisest choice." He sees Sam's thoughtful nod out of the corner of his optics, has to steel himself for what he asks next. "What did the human medics say?"

"They want to know where in my house I was keeping the radium," Sam says dryly, and Bumblebee doesn't have to listen hard at all to hear the waver beneath the words. "You guys aren't radioactive enough to have caused any long-term problems, especially only over a couple months. But I've been told to put off trying to have kids for a few years. I'll heal, Bee."

Bumblebee still can't look at Sam, at the drawn skin and heavy bruising around his eyes and the way his scalp shows through his hair in places. "I'm sorry, Sam," he whispers.

"It's not your fault," Sam says. "You didn't know."

"I should have," Bumblebee counters. "Some guardian." He leaves before Sam can answer, before he causes his friend any more damage by his presence alone.

And he tries very hard to not hear the broken "Second to none," that comes floating after him.

o o o

AN: This one's a bit personal for me, I suppose. I know that I'm incredibly safe at my job, but still, when you spend weeks studying plant casualties and what radiation can do to you if you decide to break the reactor, it becomes a bit difficult to wake up and say that you're happy you work in a nuclear power plant.