(A collaborative work. Thanks [@MrDidact]!)

Blade met with blade as Arak and William fought, up and down the deck of the ship. Arak knew he was out of his league. A rank-and-file soldier through and through, he had not learned how to effectively fight with a sword, sticking instead to spears. This mistake, he thought, would prove fatal. 

William, however, was finding it to be very easy. He had a natural aptitude for blades of various kinds, and this duel here was almost trivial. He found an opening in Arak's defense, and plunged in with his sword. Arak deflected, but a little too late, and his sword was flung out of his hands, landing a little ways away. "Ooh, bad luck," William said, circling his opponent. 

"Yield! I yield!" shouted Arak, covering his head with his arms.

"Yield?" William said, raising his sword. "You must not know me very well."

Before William could strike, a Dragon's Tooth stepped in front of Arak, shielding the man with his sword and shield raised and William felt a strong hand grab his sword arm while another arm reached for his off hand and William felt a cudgel rest on his shoulder. The cudgel was held by another Dragon's Tooth and Black Visenya gripped William's arm with another man at her side, stopping him from striking. 

Visenya snarled, the special forces ranger and not the childhood friend, commanding William, "William, stop. Disarm." He was outnumbered and the special forces troopers had gotten the drop on him. Visenya continued, her arm taut on Williams, "You might be a friend William, but I will not let you get away with slaying a member of our company. We are all working under the king's banners, I will not have comrades shed each other's blood. And don't even protest, telling me it's mutual. Both you and I know you provoked this duel and wanted a lethal conclusion. Well, I tell you now that you will stop being you and you will start being a soldier of this company. If I see you put the lives of our comrades in jeopardy again, I'll have you put in chains." 

Visenya kept her hold on William, "Believe what you want, but I'm doing this for you William. For the sake of our friendship. If you had killed Arak, you would have been condemned. The Starks would have called for your head for striking down an unarmed man, and you would be forever known as a kinslayer." 

Seeing, the look on both of the men's faces, Visenya frowned, "You didn't know? You're half-brothers, both sons of Ramsay Bolton." 

Arak was crushed. To think he had come so close to being slain, and by his own brother no less! He had wished never to see his brother in his life, and this was in no way the ideal way to meet. He fell to his knees, only barely propping himself up with his sword. 

William, however, was enraged. Lord Tyrion the Halfman was strongly suspected of killing his own father, and by his current position as Hand of the King, proves rather conclusively that the kinslaying curse is but superstition of the smallfolk. Eventually, however, after a lengthy period of thinking, removed one finger from his sword, then another, and the steel blade clattered on the wooden deck.

". . . Aye," he muttered. "Now, if you could command your men to stand down, let me pick up my sword, maybe both of us could be on our way. Don't hear me wrong, I do like embracing, but to do so with a woman I haven't married strikes of infidelity."

"My . . . brother?" Arak gasped.

"Yes, yes, we're all very impressed by your ability to hear things," growled William.

Visenya frowned and nodded at the man in front of William, who sheathed his weapons and helped him to his feet, keeping a hand on his swordbelt in case William tried anything. She nodded at the other men holding William and they disengaged, though they too were ready for the young Lord to get out of line. Visenya however, kept her arms loose at her sides, trusting that William wouldn't try anything. 

She replied to William, "Your ability to make jokes in such situations will never fail to amaze me Will. Very well. You both may go on your way. But no more duels, at least not duels fought in earnest. Arak, if you wish you may go see the Acolyte if you need medical attention. William, please don't cause any more trouble. If this goes well, Sansa will convince Brandon and Jon to reconsider your position. They will give you back the Dreadfort. If you can prove yourself. It's all you ever wanted, since we were children. Don't throw this chance away." 

One of her men went with Arak, escorting him away from the group if he needed medical attention, while the two remaining Dragon's Teeth flanked William and Visenya made eye contact with William, "I'm sorry Will. I thought you knew. Arya told me before we left. I thought they would have told you the same. Are you alright?" 

"I'm not gashed, if that's what you're asking. Incredibly annoyed, however, that I'm the last to know of my brother," said William. Gods, his weakness revealed itself then. He's too honest with Visenya, a half-Targaryen of all people. He didn't know if his grandfather or father had a proper burial, but if they were, no doubt they'd be spinning so hard in their graves they'd dig themselves back up. "Was I that obvious about the Dreadfort?" he said in an attempt to change the subject, albiet a little feeble.

Visenya knew not to press the subject too hard, and that asking further was liable to sour his mood even further so the bastard princess obliged him, she smiled a little, "You didn't have to be. Anyone would want their ancestral home to be theirs. I know I would have." She laughed, a strong almost throaty sound, not the more sedate giggling of a proper lady, "Indeed that is true. I remember the time you threatened to duel that poor squire over the honor of a dance with me. Daenyra's thirteenth name day. Can you believe it's been so long? Do you ever miss those days Will? When we were young and didn't have to worry about any of these intrigues?" She thought back to her childhood, growing up a bastard with her royal cousins and the children of the realm's greatest warriors and most powerful nobles, and how a young boy, the only heir to a dishonored house had been one of her closest friends. The thought made her smile truly. 

"Which one?" William asked, smiling with her. "I think many squires over many years are out for my blood today." He, too, did have some complaints of living life by the great game. It was one thing to be a bastard of the Targaryens, left out of the high table in great feasts or the prospect of marriage with a powerful house. It was quite another to be the son of the infamous Ramsay "the Raper", destined to have enemies he may never meet. Nearly everywhere he looked, he knew there was someone in his vision who would gladly rip his guts from his living body, simply because of a thirdhand account of him told by a lying drunk in a seedy tavern. The two of them naturally gravitated towards each other, two rowdy, dishonored kids in a sea of disapproving faces. "You know what? I think I'm done with watching dolphins for now. Maybe I'll go down to the rooms, cheat Aemon out of a few dragons. Another time, Visenya." With that, William picked up his sword, slid it into his sheath, and walked away, whistling to himself.