Need:

Warnings: Violence. Gore. Some depictions/mentions of really angry sex. And then other encounters that weren't angry. (It's consented (I won't write anything that isn't.) but they fight each other. Why?- read the next couple paragraphs after. It will hopefully make sense.)

…

On the surface, they disliked each other. The mocking and small pranks. The harsh looks they sent their enemy's way from across the table. A sort of rivalry that hadn't been shaken over the centuries.

In their inner circle, they despised each other. Scathing glares to outright arguments. Arguments for the sake of arguing, which would then come to blows. Broken glass scattered across the floor and punches were thrown while their brothers watched the fray. They knew it wouldn't help trying to separate the two. It was like they needed to fight. Only the other Norseman knew this was true, looked at their writhing forms and sighed apathetically before returning to his reading or staring at the walls.

In the back rooms, you'd swear they hated each other. Spitting curses and sneering at the others. But nothing was as horrifying as their bedrooms.

In their bedrooms, it looked like they were trying to slaughter the other. Civil behavior gone, they were fueled only by their archaic need. Instead of kisses, they bit to draw blood. Teeth clacking in the fighting, constantly fighting. Lips were torn open as well as harsh nips at their throats, causing blood to dribble down their chests. They left bruises from the lashing out and clawed at their clothing. The cloth shredded under their worn and callused hands as well as flesh beneath their nails. They snarled and fought harder at each injury they received. Once bare, the fighting grew frantic. Grinding their pelvises together while clawing and biting and smearing blood. Their language by that point was confounded and indecipherable. They wrestled back and forth, waiting for one to submit. It was never easy. Never an immediate victor. Both too proud and violent to give in to their mate. The Dane was faster while the Swede was stronger. Thrown into walls and furniture until one tired and their legs were split apart. The Swede pinned against the headboard or the Dane over the table, taken while both screamed their throats raw. They still clawed and fought and rutted until it all came undone. It never faded. After so many centuries they still needed each other. Only when their bodies were pushed over the edge did language return in the form of the other's name. Not Matthias and Berwald. Their real names. The ones they gave to each other on that shore when they were small. Not even their brothers knew of them. Only behind the sacred locked doors were they ever uttered.
They'd collapse then, thoroughly exhausted and waiting some before righting themselves on the bed or dragging their feet towards it. Both still breathless, without fail the Dane would wrap an arm around the Swede's chest. The Swede would sling an arm around to grip the man's shoulder and rest. They never spoke after having sex. They didn't need to. They knew what the other meant without speaking.

You're mine.
I'm not yours.
I thought we promised not to lie to each other.
I hate you.
That's a lie too.

In the morning, you'd swear they were lovers. No harsh words or fighting. The first awoke to soft sleep sounds and the warmth of their lover's body beside them. The second would awake to the warmth and light kisses. They'd clean out the injuries inflicted the night before and curl back up in bed, sore and content with holding the other. Some mornings the caresses and kisses turned into lovemaking. There weren't any arguments in the morning, neither fighting for dominance and instead gaging what the other needed. Each move was gentle and wary of the wounds the other had. They did not mean to inflict pain in the morning. There was no anger to hold onto.

They'd lie and remember before they were conscious of their nations. Before they were enemies. Then partners. Then enemies. Then allies. Back to the cave they took shelter in during a storm where they first made love. Or lying together in the longboats. Loving each other under the stars in soft blades of grass.

There was no victor. Pitting the King against the Lion, both would fall. In the wars they fought, the blood they spilt, no one won. No matter how hard they had tried, there was no escape. Each needed the other. There was no one to trust the same way. No one else had been able to see behind their facades. Nor had the power to break them and love them in the same moment. Tear them down and patch them up afterwards. They'd continue fighting, surely. Appearances to keep and expectations to meet but there was more. The grudges they could never release. The deaths and losses of their people demanded retribution. So in the nights they had together, when their family left them alone and Peter was elsewhere, they could gain that. So they fought. Tore at the other's flesh while relishing the taste. They had hated that they loved each other. Now they simply accepted what they needed. It wasn't love. The need and feelings were far stronger than such an insignificant human ideation.

And that was it. My first attempt at anything sexual. I hope this made some sense.
The king (of the north- Denmark) and the lion (of the north- Sweden)
Notes: they really do love each other *at which point different shippers pull out weapons* but it's different from "the humans' love". They know they need each other. And imagine the level of trust they would have after hundreds of years.
Do I need to launch into a history lesson for references? No? Alright, you slide by this time. If you want them then let me know but I think they're light enough to understand.
Any advice? I really need help with this. I hope I didn't scar anyone.