Loki finds that he is in Asgard less after the development of his friendship on Midgard. He spends time with Thor because they're brothers, that's what they're supposed to do, isn't it? He loves his brother, despite his recklessness and vanity and quick temper. He tolerates Thor's countless flaws in the hope that one day his brother will grow up. In the meantime, he talks the six of them (for he seems to have become an essential part of Thor's little gang, now) out of the messy situations Thor gets them into. He bites his tongue and rolls his eyes as Thor takes all the credit, the glory, time and time again. This is the role of the younger prince, after all – standing in the shadow of the heir to the throne, correcting mistakes privately. It's not that he resents his brother; it's that his every action makes Loki despair, though fondly. Despite appearances, Thor listens to him, truly listens, as though Loki is all-knowing and infallible. Thor will take his brother's advice, always, when the heat of battle dies down and he is calmer. In those moments, Loki is sure he could persuade his brother to do anything, however terrible, the trust Thor has in him. He hopes that, over time, his words will teach his brother restraint. That his words will make Thor understand, think like the king he will become.
Beautiful, golden-haired Sif was a childhood friend of both princes, a natural companion now. As a child, she had played the role of witch alongside Loki as often as she had played the warrior princess to Thor's ever-victorious king. If Thor had become her favourite brother as they grew, Loki could hardly blame her. Sif was always destined to become the warrior for real, it was only right that she be drawn to Thor, the most natural fighter of all. Loki's fond of her, for the most part, though he is wary of her influence on the others.
The Warriors Three were initially her friends, but that's an easy thing to forget. Thor is instantly, naturally, everyone's friend the second he meets them. That's Thor's nature. They all follow Thor without question, which Loki finds disappointing. They tease him, but there's never a real challenge in anything said, despite personality clashes from all three. Teasing. That's what the five of them do, now. Loki is quick thinking and sharp tongued, he can keep up with them. What bothers him is that the words seem less friendly when they're directed at him. Fandral is the one most likely to express it, but the Three don't completely trust him, that much is obvious.
They're in training when it gets out of hand. Sif is always able to take liberties with Loki that the Three can't, she's closer to him. She benefits from the soft spot he has for her, which means she can say more with less retaliation. Their teasing arguments are friendly and warm, even though her closeness means she has more ammunition. Loki and Sif have just finished sparring, matching staffs, when Volstagg starts to make comments about Loki's inadequacy as a warrior. He scoffs, mocks in return. Fandral suggests he hasn't faced Loki because the poor baby prince wouldn't stand a chance. Loki can barely be bothered to roll his eyes at that. Sif joins in, it's comfortable, but Fandral encourages her to say more until she pushes too far. She's comparing him to Thor, wondering why the brothers never fight. There's an uncomfortable implication there. When Loki bites back an insult in return, it's laced with venom. There's no trace of their friendship left. The argument escalates, all raised voices and threats, insults designed to cut deep. Fandral edges away from them as Thor steps forward, uncertain. Sif says it outright, then. That Loki is jealous of his brother; that he will never match up to Thor in any way. She flinches as she hears the words leave her mouth. There's a pause. Loki's mouth is dry, words fail him. He hears Sif call his name as he walks away, but refuses to turn around.
When he finds Thor and the Warriors Three the next day, Thor lays a hand on his shoulder softly, briefly; nobody says a word about the argument. They talk; Thor telling of some new quest he has planned that will no doubt end in disaster. Loki doesn't look up as Sif arrives, doesn't react to the little noises of surprise his companions make, though he can feel Thor's eyes boring into him. Sif sits a little too closely to him at his side and touches his leg briefly as she whispers her apology for hurting him. Loki closes his eyes for several long moments and she leaves, moving to sit opposite him with Hogun. When he opens his eyes again, she's tucking newly-ebony hair back behind her ears and he has to swallow hard to fight the sickening guilt he feels. He joins the conversation more hesitantly than usual, aware of the disapproval radiating off his brother in waves. Sif, for her part, smiles softly at him and acts no differently than she normally would.
The Warriors Three are now more cautious in their insults to Loki. There is little difference in Hogun, but he was always one to keep his distance. Volstagg and Fandral are difficult to read, but they seem to resent him. Thor is more distant than ever before. Sif is the same as ever, but Loki can no longer look at her without acknowledging a part of himself he isn't entirely comfortable with. He tends to avoid her wherever possible. He avoids Asgard entirely for extended periods, spending more time with Tony.