Ghosts can go quite a long time without a recharge. It's not something known to Danny. For once, this isn't due to his inexperience; no, most ghosts don't know.
This is because ghosts recharge naturally, just by being in the ghost zone— hence why they never strayed overly far from Amity Park's borders despite the catastrophic potential of their spread. Some could get a temporary boost from emotional output, but it never lasted. Consistently as they grew further, they grew weaker, and when they were brutally beat down (perhaps by a certain Phantom) they needed that glowing green essence of their home.
Danny's awareness of this came in stages.
The first stage was the weakening. He spent the first few months of his halferlife mostly figuring stuff out; sure, fighting the (eventually relatively) weak ghost creature that came to haunt the halls, but even then he did that primarily with his fists (albeit floating).
The main usage of his powers was accidental; a dash of invisibility here, a sprig of intangibility there. Enough to stress him out emotionally, but nothing that drained his ghost side physically. Routine exercises for a ghost, especially one with a solid body it could take excess energy from.
The only compensation Danny had to do was eat a little more. Considering everything else that was going on, he didn't even think to question it as a compensation for the energy of his ghost side, but saw it as something normal. After all, teens were bottomless pits, ghost side or no; it was a nice, familiar constant, a good normalcy.
...Even if, as the ghost fights increased, so did his hunger.
It starts as a little extra on his plate, a few bites more.
His parents notice when he starts to take double portions as he's fighting more fully fledged ghosts. Bitterly, Danny just wonders if they notice through food shortage and bills; it's not like they come up from the lab often.
Normally, he'd tell himself not to think about what they were doing in the lab when he was trying to eat, but now… now he's just so hungry that the nausea just doesn't matter.
"My son's a growing boy!" Jack splutters, unspeakably proud as he claps Danny on his skinny shoulder, knocking some of that precious food out of his mouth. "Finally swimming in my end of the gene pool," Jack laughs, puffing his chest up.
Danny takes in his father's broadness, thinking of his own lithe style of fighting. I hope not.
The issue with them noticing is when the ghosts continue to escalate— because his intake thusly escalates… and not even to scale, as though his body previously was boosted just fine but the solution of food is temporary, at least to some degree.
Then it was just another worry on his shoulders. Another of those traits that constantly nagged and bit at him— When will your parents notice? When will they put it together?
When he voiced those concerns, the need to consume such noticeably vast quantities of food, Sam and Tucker unanimously shrugged.
"They'll buy that teens are bottomless pits," Tuck informed around a large burger (demonstratively of his statement, really).
"Your dad'll just be happy that you're," Sam paused, inhaling, then continuing in the most Jack Fenton-ly deep voice she could muster, "filling out to be just like your old man!"
Danny managed a snort, eyeing his own burger, painfully hungry gut flipping in anxiety, but accepted it with a nod. After all, it wasn't like his parents had noticed anything about him that was more obviously ghostly, and there were plenty traits to name.
It was as though the universe took offense at that thought, or perhaps at the idea of letting Danny Fenton live his life easily. It didn't matter the motivation of the universe's whims, it just mattered that the hunger escalated.
Danny was inhaling food 24-7 now, enough that his worries about his parents noticing were coming true. Granted, it had taken them quite a while, but eventually they noticed he was never without a carb heavy snack. He could only keep that on the down low so much, particularly since using his powers made his stomach twinge in its constant state of hunger.
It was getting worse, food just a temporary solution. Danny'd read enough on ghosts to consider the portal (he may have been a C student, but he wasn't a total idiot)— but that didn't work; it brought an energy buzz, but it didn't sate the hunger. It wasn't the solution either— though he'd find the real one soon enough.
A fight with Johnny had gotten out of hand, lead to Danny ways away from Amity after having chased that stupid ghostly bike down a road stretching into nowhere. Needy of help, Danny had shouted at Johnny, asking of hunger, and Johnny had just shrugged and said "ya should be gettin all that food from the zone," and then he'd shrugged again and kickstarted his motorcycle into gear, riding off with a flare of green flames, tailed hotly by Danny Phantom.
Exhausted and grasping at his stomach, Phantom began the flight home, drifting in a wobbly way.
He paused his mental moaning and groaning when the air turned sweet, as though someone had set a flytrap of honey. The halfa narrowed his eyes, practically walking on the air as he attempted to locate its source.
...A deer. Smashed.
Smashed was one way to describe it. Another more gorey way existed; ribs exposed to a baking sun, maggot eggs rooted in seeping flesh, labored breathing that oozed blood with every huff. Full of effort, the doe turned an eye towards him, full of fear.
Smelling so good.
It was paradoxical; Danny was drooling unrelated to throwing up, even though he was doing that too.
Most strangely, it was his first experience of satiation in a month. Just being near the creature's rotting flesh as it panted its life away was enough to bring fullness to his belly, even as he expelled all the food he'd eaten that day before he left.
Who to go to, Danny wondered in bed. His parents knew not about whatever that was— even ghosts hadn't known, Johnny hadn't known. A halfa thing? It was a tentative conclusion, but one likely enough to consider. After all, Johnny spent enough time in the human world to know enough about "ecto fatigue" (his parents dubbing of the phenomenon).
That, of course, left one person.
…Well, Vlad certainly couldn't have him as his weird son if he starved to death, right?
—That was the leverage he was holding now, at least. "I won't do it," Danny informed him after Vlad gave more oozing offers of "well if you'll just be my pupil." "Besides," he continued, "you seem to know what'll happen— can't be your son if I die fully, and do you really think dear Maddie will look to you if I do?" Danny made a retching noise to go along with his sarcasm.
Vlad gave in. "Follow me," he hissed, sliding back into that role of authoritative power, a cocky rich man rather than a frustrated ghost.
Hesitantly, Danny trailed, easily following Vlad directly through the ground to his secretive basement (not so secret, given Danny knew about it too).
"What does this have to do with it?" Danny pondered, eyeing… cages. A little set of small cages— stuffed with squeaking, writhing rats. Some of them were laying in the corner of their cages— something told Danny they were unconscious, but not dead.
Danny recoiled at the deafening confined scrabbling. "Didn't know you were one for pets."
Vlad ignored him, phasing a hand through the cage to pluck a rat up, thumb resting against its small throat.
Danny was becoming highly uncomfortable with the way the gray rat in Vlad's hand had its eyes blown wide with fear, tiny voice squeaking as it squirmed. Tittering and shuffling and feeling much like the rat, Danny just ran his mouth— "what, you got a snake instead of a cat? Or maybe your cat caught all of these, instead? Or—"
The squeaking became more frantic, and Danny's blue eyes snapped to the rat in Vlad's grip. His thumb was pinned to the thing's throat, cutting off its air, causing it to panic.
Slowly, its struggles stilled, each cry becoming more wheezy, each movement of its tiny paws becoming more leaden.
The sweet smell returned, and Danny breathed it in involuntarily— and felt full again.
Vlad smiled sharply, edging his grip off the things throat. It breathed, but was knocked out— the man callously tossed it back into the cage. Danny's blown eyed gaze followed it.
"We can't help it," he crooned in a faux gentle voice, honey and oil oozing from it equally, "we're halfas. We need something on the brink, like us; not fully dead, not ghost energy nor meat. Neither would completely do it."
Danny stared at the unconscious rat, and he was the one breathing hard, pain in his lungs rather than his stomach.
xXx
Prompter: heartbeatslows
Prompt: "I can't help it, okay? I'm a halfa! …I need this to survive."