Heimdall can see Jane, and Thor tries to convince himself that this is enough.
It's been three weeks since he smashed through the bifrost, saved Jotunheim, earned back his father's respect-- and lost Loki. Thor spends much time sitting with his legs dangling over the edge of the jagged drop of the destroyed bridge. He's working on convincing himself, day by day, that his traitor body isn't going to lean forward past the point of return-- that his hands will not suddenly push against the edge and hurl him into space-- that each time he will sit down carefully and not leap ecstatically into [swirling] space.
He just wonders what would happen.
Heimdall lets him sit, doesn't even comment after the first time. Unlike his feelings about Loki, Heimdall trusts Thor because he can see right through him. And maybe Thor stays on the bridge precisely because he knows that if he ever planned to do otherwise, Heimdall would know.
Thor asks about Jane sometimes. Talking to Heimdall about Jane is easy and requires no risk, like swinging his legs over the edge of the bridge. Sometimes Heimdall can even manage to bring echoes of what Jane is saying up to them, although he insists that he wouldn't be able to forge a line of communication between them and a human on Earth that worked both ways.
Talking about Jane is sitting, but that implies the existence of the other option: falling.
In the end, Heimdall pushes him. “It is possible that I could forge a two-way communication channel with an Asgardian, he says, offhand. “If such a one were open to the connection.”
It's like being punched in the stomach; it knocks the wind out of you even if you knew it was coming.
“I--,” says Thor. He stops.
“I suspected as much,” says Heimdall.
Thor doesn't watch as Heimdall makes the connection; he doesn't want to see whatever physical manifestation of this conversation might exist. He stares into space until Heimdall taps him on the shoulder and nods. Thor opens his mouth and, ludicrously, the first thing that comes out is an excuse.
“You visited me, when I was in exile.” It's lame as excuses go and Thor knows it. Loki's exile, if he even sees it as such, is self-imposed.
Thor hears nothing. “Are you sure he can hear me?” he asks. Heimdall merely nods.
Thor takes a deep breath. “I forgive you,” he says. He had intended it to sound grave and monumental, but instead it just sounds like every time Frigga had forced him to apologize after pushing Loki down the stairs or something as kids.
Loki's voice is quite, not angry, not upset, but not forgiving. “Don't.”
“Don't what?” As if he doesn't know the answer; it would be obvious even if the syntax of the conversation didn't leave this as the only option.
“Don't forgive me. You'll regret it.”
“What the hell is that supposed to mean? You don't want me to get my feelings hurt when you prove again that you're a traitor? Or are you worried that if I forgive you, you won't be able to stay angry?”
Silence, so long that Thor can't help but try to picture his brother. Is he dumbfounded? Silently weeping? Not paying attention to the conversation at all?
Loki says, “We will see each other again, brother.”
“He's going,” mutters Heimdall.
“What? Make him--”
“He can conceal himself from me at will. Does this surprise you?”
Thor tries to be apprehensive about what Loki had said, but can't quite manage it. “Until that time, then,” he says to the air, and turns back towards the palace.