Fionna can hear his muffled cries from above which gives her strength to make an effort on opening her eyes. It isn't the ocean so it doesn't hurt, but everything is still blurry. She looks up and sees the bottom of the rocks, she then looks down and can see the skulls with their mouths open and hollow eye sockets. Why are they screaming?!
Unless…they are calling something or someone.
AIR.
Fi starts kicking her feet to take a sweet gulp of air, but something cold grabs her leg. She can feel the tips of claws sharply dig into her skin making her let out her last breath of air. Quickly, she lost consciousness and feeling, letting her body be dragged away by this unknown being.
Up above Fi's air bubble floated to the top and popped in front of Flame Prince's face. He bites his lip hard and attempts trying to look through the water once more. He can't see her and the skulls' screams are just annoying him already. He stands up, closes his eyes and takes a very deep breath. He shakily exhales without opening his eyes and fills his head with Fionna.
Quickly he mutters, "Power of love keep me alive," and jumps in the lake.
Every part of his body felt like it is being stung by a thousand bees and pierced by needles. It was the pain that made him open his eyes as soon as he was surrounded by water. The skulls' screams are muffled through the water, now he can concentrate more easily. He turns his body 360 degrees to spot any sort of clue where Fionna is. He immediately spots a hole about 10 feet in diameter and swims towards it. Hopefully, at the end there is air and her.
The tunnel is dark and the further he went inside the quieter it became. So quiet he can hear his heart thumping loudly from swimming and pain. About a few meters later he finally pops his head out of the water, breathes, and rushes to the shore. He can already tell he is in a cave, but can't tell what is around him for he is in his doused state and near to losing consciousness. His body feels heavy as he falls forward, unable to lift himself up.
No, I can't faint now! No…I'm near past fainting…
"I can't die…" he grunts, trying to spark a flame within his hands. The flame on his head drooped over his eyes, he attempts to dry it and try making a fireball again. No luck. If he faints he'll die.
Slowly, Flame Prince gets up and starts using the rocky walls for support and walks forward. Hopefully, he can dry himself by the time he finds Fionna. His feet drag across the flat ground which is coated with black causing him to accidentally kick a small rock. It makes a small echo throughout the cave making him pause. He's been looking down the whole time that when he looks up only then did he notice a small light peeking from a corner. He moves a little bit faster to reach that light, leans on the wall and peeks behind the corner.
Through blurred vision he can see the shape of Fionna's body and the color of her clothes lying on the ground. In front of her stood a large figure about nine feet high that smelled like fish. He can't make out what the creature looks like, whether it held weapons or even needed them. If he rushed out to Fionna in his condition they will both die under the hands of this thing?
Helpless. He feels helpless.
So far the creature just hovered over Fi; it even poked her to check if she is still knocked out. He watches it stomp inside another cave and heard a clang of metals. It brought back a pile of wood and a pot which he hears the sloshing of water coming from. Oh, Glob, he's going to eat her!
He pauses when he hears flint rub against each other causing a spark. It's actually a good thing this monster decided to not eat Fionna raw. He hears fire start licking the wood and crackling, calling for him. He turns to where Fi was lying and saw that she is gone and that the creature is carrying her to the pot!
With a gulp Flame Prince steps out revealing himself. The fire is just two meters away from him as the monster is three. It roars at him and drops Fionna sloppily on the ground. Flame Prince clenches his teeth and tries to sprint towards the fire. The creature stood there looking confused while the Prince carries his body over right on top of the fire. The warmth is incredible and he no longer felt heavy. He takes a piece of wood that had a flame burning on the top, turned for the creature to see, bit where the flame burned and swallowed it.
"I'll be taking my girlfriend now," he says with a scowl. "Now, I can't let you off easy since you tried to eat her," with that said he threw a fireball, but the creature slithered another direction closer to Flame Prince.
Now he can see what the monster looks like: head of a crocodile with a mouth filled with thousands of two centimeter long sharp teeth, muscular arms that ended with webbed hands as well as huge claws and a long tail that could be used to knock him down in an instant. It's body is covered in scales and a nasty odor.
Once more it roars and charges to him with a swing of it's tail. Flame Prince puts his arms up for defense, but it still knocked him against the wall leaving an indent. He begins to throw multiple fireballs at the creature which released a ton of smoke as they hit it. Through the smoke it pounced at him with little wounds and picked up the pot of boiling water to chuck it at the Prince. Immediately, Flame Prince spits fire to convert the liquid into steam.
They stand a few feet away and stared into each other's eyes with hate and fury. Their silence is broken when a voice from behind the creature yells out, "I'M GONNA MAKE YOU INTO SASHIMI!" Fionna had woken up just now, saw the creature hovering over her boyfriend, got out her sword and jumped on the creature's back. It tries to throw her off, but had no effort. Fi clung onto it's fin for the scales made him slippery.
"Actually, I prefer my fish burnt," Flame Prince throws fireballs at the creature's chest as Fionna tries slicing and dicing with her sword at the back. The creature finally falls forward, twitching as Fi stands triumphant on it's back and holds up her sword, "I…am…not food!"