After watching the trailer for Dragonborn, I got the urge to write this. Obviously it's not canon, but it will be in my mind.
He bolted upright, his eyes flaring open. For a moment Perseus forgot where he was. A quick look at his surroundings, however, brought him back to reality. Half of the province of Skyrim was visible below him; a spectacular view that could only be seen from the Throat of the World, the place where he had been resting. The peak of High Hrothgar was a strange place to take a nap, true, but his Nordic blood and warm clothes protected him from the cold.
The mountain peak was his favorite place in Skyrim for two reasons. One, of course, was the incredible view. The other was its security. Perseus had vanquished hundreds, if not thousands of opponents, but there would always be someone out there who desired to kill him. Since his defeat of Alduin, the Throat of the World was now guarded by two powerful dragons, Paarthurnax and Odahvling. That, and its isolation, made it the safest place in Skyrim, and one of the only places where he could truly find peace.
A voice to his right reminded him that he was not alone.
"What's wrong?" Serana asked, who had been dozing until his abrupt awakening. Perseus couldn't help but smile at her. He'd only known for for about a month now, but in the time they'd spent together he'd gotten closer with her than he ever had with anyone. It had been strange, at first, being companions with a Vampire. But he'd soon realized that she wasn't like the others he had met (and been forced to kill.) When she realized what her father's ambitions would mean for the rest of Tamriel, she had given up everything to fight against him.
Since they had become allies, Serana had saved his life multiple times. Their relationship quickly became more comfortable and personal, and before long they were confiding in each other about their difficult (in Serana's case, disastrous) personal lives. When confronting Harkon, both had declared their complete loyalty to the other.
After leading the Dawnguard to victory over the vampires, Perseus had encouraged Serana to cure herself of her Vampirism. She had been taken off guard, but eventually decided to seek out Falion for a cure. While discussing the matter with her, Perseus had felt that finding a cure would have been best for Serana, though his high opinion of her would not have changed regardless of her decision. After she had left, however, he had begun to fear that she would regret finding a cure and resent him for it.
His fears had proven unfounded, however. She returned to Fort Dawnguard cured, and to his great joy Serana was very happy with the change, saying to him that "I feel like I can breathe for the first time since I was turned. The world is alive, and so am I, for once." Perseus had never been happier.
Despite losing her Vampirism, Serana remained just as powerful as she was before. It seemed that being a pure-blooded Vampire for so long had allowed her to retain her abilities even after she had been cured. She retained the ability to cast Vampiric spells and still possessed a high resistance to cold. Her other powers and her skill with the dagger he had given her, the Blade of Woe, were undiminished. But now she could also be affected by his Restoration magic, proving that she was, indeed, alive.
There was something growing between him and Serana, and Perseus had been hoping that they would have some peace for a change, allowing them to explore their feelings for each other. He was definitely both physically and emotionally attracted to her, and he had a feeling she felt the same way about him, but he wasn't certain just yet.
And now he had a feeling that their relationship, or at least, the forming of their relationship, would have to be put on hold. After Serana had returned, cured, they had spent the previous few days traveling through the province peacefully. But now, he feared, that would soon change.
He turned to answer her question.
"I think I just had a vision," he explained, "And it wasn't good."
She looked at him curiously. "You mean, a nightmare?" she questioned.
He shook his head. "No. With all I've been through, I've had plenty of nightmares. This didn't seem like one, though. It felt too lucid. I've never had a dream that real before."
"What was it?" she asked, concerned.
"It was brief, very brief. I saw dragon skeletons scattered on the ground. Their souls were being drained into a man with armor I've never seen before. I could sense his power though, and his malevolence. Whoever he is, he's bad news."
"I don't understand. How can you be so certain this was a vision? It could have been anything else…a hallucination, a lucid dream. How can you know?" she asked intently.
"I can't explain it…but I somehow, I just know. Perhaps the Divines are trying to tell me something. I think…I think whoever he is, he might be a part of my future. And if my gut instinct is right, I'll have to confront him someday."
"If you do, I'll be at your side," she promised him. "But….are you sure you're not wrong?"
"Almost certain," he replied gravely.
"It doesn't make sense though, you said you saw him absorbing Dragon souls. But I thought you were the only one," she said, a look of worry etched on her face.
"So did I. But perhaps…" he began, looking out across his frozen homeland and pondering what the future held.
"Perhaps I'm not the only Dragonborn out there."