A/N: This story is set after the events of the MCU films "Thor: The Dark World" and "Avengers: Age of Ultron". I am also uploading this onto Ao3.

Disclaimer: I do not own the names of characters/places, etc. These belong to Marvel.

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Arriving back in Asgard, upon the Bifrost, Thor was filled with hope and determination. Surely home in Asgard he would be able to find answers. His father would forgive him for his actions in the Dark World, although Thor had a feeling forgiveness was no longer necessary. The All-Father would heed his words and worries regarding the Infinity Stones, and would most certainly have knowledge to add.

"Heimdall," Thor said as he stepped out of the Bifrost. Heimdall's hall, the entrance hall to Asgard, shimmered and shone in the starlight. The entrance hall at Stark Towers was tall and white and sleek and 'modern', as Tony called it. The entrance hall to Clint's family home was narrow and dim and full of odd shoes and boots and coats and bags and umbrellas. That was home to Clint, and to Tony. That was what coming home mean to them. This room meant homecoming to Thor.

"The prodigal sons returns," Heimdall said, and he and Thor embraced.

"How is Asgard? All is well?" Thor asked, only now realising quite how much he had missed his home.

"Much more so than upon Midgard, from what I have seen from afar," Heimdall said.

Thor gave a nod, "Aye, trust those eyes my friend, for lie they do not. But peace reigns once more upon Midgard, the day saved by my companions and I."

"And the trouble created."

Thor smirked, "Now, now, they are but boys in this ancient universe. Children. They know no better."

"They do now," Heimdall said.

"That they do," Thor replied, "Now, if you shall excuse me, I must find my friends, as Midgardian food has nothing on the mouth watering delights upon which we feast on high."

"You returned without with cares or questions?"

"Simply seeing you once more has had me put my cares aside," Thor said, wondering if Heimdall held the answers to the questions Thor had to ask. "But the universe is in no hurry tonight. All can wait until morn."

"Enjoy," Heimdall said, "Your return shall be most welcome. Know I am at your service, should such be required."

Thor clapped Heimdall on the shoulder and looked up Rainbow Bridge towards the palace. "Thank-you my friend. It is very good to be home."

...

An hour later the Prince of Asgard sat in a small private dining room, sharing a magnificent roast boar and trimmings, along with the finest mead that could be procured in a hurry, with the Warriors Three and Lady Sif. All were most interested in the tales of Thor's latest exploits upon Midgard, the Warriors Three in particular. Thor noticed that Lady Sif seemed somewhat distracted, but she smiled and laughed all the same at Thor's recollections of his time of Midgard, and as he ate and drank, Sif's unusual unease fell from Thor's mind.

"But what does our rebellious Prince do once more upon home soil?" Fandral asked.

"Answers are required to questions I do not fully understand," Thor said, taking a large drink from his tankard.

"Questions of what nature?" Lady Sif asked.

"Of movements in the galaxy," Thor said, "Of coincidences and strange occurrences too many."

"For one who has downed as much mead as you on this fine evening," Fandral said, "You still manage to surprise me at your aptitude for thinking thoughts in a straight line, and having them come out of your mouth in the corresponding order."

"I for one," Volstagg said, "Have had much too much to drink to have any thoughts in any order, unless that thought is; another!" Volstagg smashed his tankard upon the floor, and the others all joined the action and laughed.

Thor looked at each of his friends as another round of mead was brought in. The jug was passed around and each poured their own. Thor poured his tankard full of mead and looked at the devoured meal of roast boar, and around the table at his ever-true friends. It was indeed very good to be home.

...

The meal and associated revels lasted until well into the evening, and once the friends decided to leave, Thor was more than ready to retire to his own chambers to bath and sleep. On his return to his chambers, Thor slowed to look out of one of the windows, glancing at the view out over Asgard and down to the waters below stretching into the stars and the void beyond.

"Thor?"

Thor turned. "Lady Sif," he smiled, "I was headed to my bed, but even the slightest blink of time away from Asgard gives one a renewed sense of gratitude for her beauty. There is no where in the universe such as this."

"I do agree," Lady Sif replied.

"What is it?" Thor asked, leaning against the window sill as he looked back at her. "There has been something on your mind all night."

"Then you are more observant than our other companions," Lady Sif said, glancing up and down the corridor. It was empty, save for the two companions.

"Did you follow me?" Thor asked, realising the Sif did not have any reason to be in this part of the palace at this hour.

Sif nodded. "Forgive me, but there are things you must know. Things that cannot wait."

"Lady Sif, I am quite sure that a few more hours, for rest,"

"Could be a few hours too many. Please Thor, we are running out of time. I have told no other, but now the secrets which I hold are eating me inside. We cannot speak here. Follow me."

Curious, Thor followed Sif through the palace in the general direction towards his chambers, but she pulled him aside into a small, empty anti-chamber, before reaching the royal quarters. The room included a window with another grand view of Asgard.

"Thor, I need you to promise me that you shall not act out or judge what I have or have not done in any way before you hear me out," Lady Sif said, "It is imperative that I tell you what you need to know tonight. There are many questions to which I know the answers not, and the holes in my knowledge are many, and in some cases, quite large."

"Lady Sif, you have my assurances, there is nothing,"

"Loki is alive," Sif said, holding Thor's gaze.

A thousand questions filled Thor's mind at once, the most potent being that that was not possible, and if so, how? For he had held Loki, he had felt the breath leave his brother's body.

"He's been impersonating your father almost since he was assumed dead in the Dark Realm," Sif continued before Thor had tome to respond. "I do not know where the All-Father is, or what Loki has done with him. But Loki has been a good king and ruler. He is good at the job, Thor. He's very good. He is just and fair. Asgard is peaceful and prosperous. None suspects that it is not Odin upon the throne. It took even I a very long time to notice that something was not quite right. But Loki is sick, Thor. He's very sick."

Thor stared at Lady Sif. He felt a strange coldness spreading through his body. His stomach tightened, and he regretted the fourth helping of boar. "What are you saying?" Thor asked.

"He now only takes council when he must. He makes so very few appearances. Others have began to question the All-Father's health. He is becoming conspicuous by his absence. Loki knows this, but he is so sick…"

"W - what are you saying? That Loki is alive?" Thor asked.

"I do not know how," Lady Sif said.

"I held him, Sif," Thor said, forcing back tears, "I held him and watched him die. It must be an imposter. A skrull or some form of magic or,"

"It is magic," Lady Sif said, trying to stay calm. It would not do for both her and Thor to become emotional."But it is Loki's magic. I know him, Thor. I know it is he."

Thor clenched his jaw. He had mourned Loki. He had blamed himself for his brother's death. "Where is my father?"

"I do not know."

"Have you not asked Loki?" Thor asked.

"He refuses to answer, although of late, he barely has strength to eat. One might suspect that he does not trust me with his secrets, but I do not believe that to be the case. I cannot help but feel he is protecting me, most likely to protect himself in some way, knowing Loki as we do."

"Protect you from what?" Thor asked.

"I told you before, Thor, there is much I do not know. Whatever Loki knows he has not said. Please Thor, he is very sick."

Thor folded and unfolded his arms, unsure as to what to do with himself. "How did you find him?"

"I went to him one evening, expecting to see the All-Father. He had been seeming particularly remote and vague. Folk are still keeping their distance, presuming that it is the loss of his wife and son, and exile of the other son that is causing him such grief, and thus he prefers to keep to himself. I went to console him, and found Loki instead."

"Does Heimdall know?" Thor asked.

Sif shook her head. "Loki has been using his magic not only to resemble the All-Father when in public, but also to disguise his own identity as that of your father. Ask me not to explain how it is done, or how much energy that requires, for I cannot answer."

Thor shook his head. "I cannot believe…"

"Please," Lady Sif said, "You must see him."

Thor nodded and swallowed. "You see Loki regularly?"

"Yes," Lady Sif replied. "Early on, it was not so much, but as time has passed and he has grown weaker - I fear for him, Thor."

"Do the guards not suspect anything?" Thor asked. "You going nightly to his chambers?"

Lady Sif shook her head. "Did you not ever wonder how Loki used to so often appear? You would think 'how did he get here?' having not seen him enter? No one knows this palace like your brother, Thor." Sif leant against the wall and a slight crack appeared in the stonework before opening into a door. Sif pushed it aside. A narrow spiral staircase was inside, a blazing torch resting beside the entrance.

Thor looked back out the window, and realised where they were. "Loki uses his own room, and not my father's?"

"There is another passage which joins the two," Lady Sif explained, taking the torch out of the holder. "Your chambers too. And those of your mother's. As it turns out, Asgard is full of hidden passageways we know little of. Come."