Sure! But, to make it as permanent as a tattoo, magic is needed

Jon grabbed the extremely special quill and addressed his sister.

"This is an...ancient magical artifact from Old Valyria," He informed her, stretching the truth in the process. "The old power carved into it will allow me to grant your wish. But, to make it work in full, I will need a bit of your blood and mix it with mine to make the magic bloom more effectively. Think of it as an ingredient for Blood Magic but don't worry, I don't need much."

Arya raised an eyebrow at that but then shook her head a moment later and looked at him with a determined look. "I would sacrifice more than a small amount of blood to break that betrothal," She declared. "So, go right ahead Jon."

The Bastard of Winterfell nodded and went to look for a small recipient where he could mix their blood. In the end, he emptied the bowl of water that is kept in the chambers for face washing after waking up in the morning. Then he started looking for a knife and realized he didn't have one in his room at the moment but then Arya showed him the Valyrian Steel dagger that he had gifted her, a resolute look on her face.

"Hmph," He muttered. "Very well, but let me do this part. Blades made of that metal are extremely sharp so we need to be slow and precise right now."

His sister nodded in understanding and extended her arm for him while removing her long sleeve to expose her skin. Realizing it wouldn't be a good idea to cut her in an easily visible place that is usually exposed in public, at least until his control over Arya is absolute and publicly acknowledged at that, he tugged at her shirt a bit further and exposed her right shoulder. After all, his sister's strong arm is her left one.

Then, he did his best to delicately make a shallow cut on a spot in her shoulder that wasn't as important as the rest, at least as a vital area. Arya flinched slightly but didn't cry out, taking the pain and bloodletting in stride as the crimson liquid started flowing into the bowl that Jon was carrying with his other hand. A couple of minutes later, he had gathered enough drops of blood from her.

Once that was done, he moved to wash her exposed shoulder with a wet piece of cloth, the movement of his hands tender as he cleaned up the wound. Arya sighed at that, sounding calm.

"After we are done here, I will call for Sarella Sand to have her take a look at your injury and to apply some of her medical herbs," He said softly. "You will be healed up in no time."

"Sarella...you mean the daughter of Prince Oberyn of House Martell?" She asked with a raised eyebrow. "I have been meaning to ask you about her, actually. Why did she join you in your travels and how exactly did she learn the skills of a healer?"

Jon paused, trying to decide how to answer her query as much as possible without being too direct. In the end, he shrugged. "After I grew much richer than before during my first merchant voyage to Sunspear, I gave her and her Summer Islander captain of a mother a...deal that they could not refuse," He admitted. "And it has paid off well. Swan Ships made from the rare, precious woods of the Summer Islands are among the fastest and sturdiest vessels in the known world, after all. And as part of the deal, I hired Sarella to be my personal healer. As for how did she learn those skills, she managed to hide the true nature of her sex for a few years and succeeded at learning much in the arts of healing while staying at the Citadel. That kind of determined dedication seemed to me like it had to be rewarded, and I hadn't had a single reason to regret hiring her services ever since," The Bastard of Winterfell explained.

Arya smirked at that. "She seems like a clever woman to be able to learn to her heart's content right under the Maesters nose. I think I would like to talk with her later."

Jon chuckled. "That would be easy to arrange. But for now, let me add my own blood into the mix."

And with that, he moved his sleeve so that he could look at his left forearm and carefully slashed at it, letting the blood drip into the bowl. As he waited, he thought once more about his experiments with the quill. He had been able to determine that it had a seemingly inexhaustible source of ink flowing from its tip, likely a result of it being a godly-powered object. However, as he figured out early in his claiming efforts, the ink doesn't last forever, especially if the text is exposed to the salty breeze of the seas. Thankfully, after claiming Yna, the first Blood Magic Sorceress in his service, she helped him come up with a method to make the ink permanent on someone's skin: by mixing it with the blood of the claimed and the blood of the owner and then finish the process with a ritual.

They were still not exactly sure as to why that ensured the writing would effectively turn into a tattoo on someone's body, but Yna suspected it had to do with the fact that most of Valyrian magic was rooted in blood and fire and since it was a Valyrian god that granted him the godly artifact, that could explain why it reacted in such a way with the enchanted ink. Curiously, however, even with those magical additions, no one else, not even his claimed sorcerers have been able to use his unbreakable quill to claim something else in their own name so, if Yna was to be believed, that was one of the reasons why his own blood was an important ingredient to ensure the permanence of the writing: as far as Meraxes was concerned, that quill was his by right and its new powers of ownership were expanded when he was willing to pay extra, so to speak, with the spilled blood that the quill would recognize as that of its owner and some additional magic to go along with it.

So, after his first successful experiment on that matter nearly 5 and a half years earlier, Yna managed to use a Blood Magic ritual on his open wound so that the magical essence would flow into his veins and ensure he wouldn't need her constant presence to produce the tattoo-like writing results himself. Well, at least as long as he could get the blood of the person he wanted to claim as well so that he could mix it with his.

And it was with that thought in mind that he started washing his new shallow cut on his forearm, now that enough drops had fallen into the bowl. He took a deep breath after a bit and turned to look at his dear sister.

"I am ready," He announced. "But after I do this spell, there will be no turning back so I feel like I need to ask you one last time: are you sure you don't want to marry Theon Greyjoy and become the ruling Lady of the Iron Islands as a result?"

"Not even remotely," Arya replied, her tone firm. "So please, brother, save from that fate and let me join you in your adventures."

Despite everything, Jon couldn't help but smile warmly. He felt closer to his favorite sister at that moment than he ever had and he suspected the feeling was mutual.

"Very well then," The Bastard of Winterfell said with a nod. "I will be more than happy to have you join me. A new chapter of your life is about to begin but know that I will always do my best to take care of you. And trust me, we will have a lot of fun together," He added with a grin.

"I can't wait," She declared while grinning back. "Now get on with it."

"Your wish is my command, my dear sister."

And with that, Jon soaked the tip of his god-given quill with the mixture of their blood. He waited a moment for the enchanted ink to combine with their life-giving fluids and then asked her to remove the glove of her left hand. Arya obeyed him without hesitation and opened her palm to him. Finally, the mortal champion of the Valyrian God of Dominance and Ownership wrote the name tied to his identity on his sister's palm, watching as the now dark red colors shone brightly for a moment before the letters were permanently seared into her skin without causing her any pain.

The deed done, he looked up to see that his sister's eyes had widened considerably as she looked at the palm of her hand.

A/N: Well, this was a bit exposition-heavy but well, the lack of easy, modern tools that produce tattoos in Planetos in a quick manner made me think Jon needed a method to make the writing permanent without it. And while tattoos do exist in this world, it was much more complicated to get them done the medieval-like way. So, I decided to work around it and combine the written powers of the quill with the Blood Magic from the series to make the words permanent on the skin when Jon wants to.

Anyway, Arya has officially been claimed by Jon. How do you think she will react to that development in the very next chapter? Moreover, how do you WANT her to react? I am curious to read the feedback.

Regardless, I will try to update soon but like I have said, reviews have a way of inspiring me to write faster so, well, you know what to do if you want a continuation for this chapter sooner, lol.

I hope you enjoyed it and until next time.