Thor goes to see Eir first. He never forgets what she tells him. “Mortal lives are short, Sire,” Her gaze is full of something Thor might call pity. He has never been pitied before, and finds he doesn’t care for it. “It is not our duty to interfere with the affairs of Midgard.” There is censorship in her tone, now, and Thor knows that she, like so many others, does not approve of how he has chosen to spend his time. He doesn’t care.
When he leaves, Thor does not look back.
He arrives on Midgard at night, and Thor goes straight to Jane. As he climbs into bed she curls into him, and Thor cannot help but smile. He doesn’t sleep that night, but the time spent with Jane’s reassuring weight pressed into his side settles him like nothing on Asgard could.
In the morning, Thor simply tells Jane that he had business on Asgard. He doesn’t tell her what that business was.
Years pass, and Thor can sometimes forget what is coming. If Jane’s hair is a little bit darker, and her skin a little bit more wrinkled, it is meaningless. She is still the most beautiful woman in the entire universe to his eyes, and Thor knows that will never change.
Tony’s hair has begun to turn gray in places, and Pepper has a streak of white at her temple. It does not change who they are, and how Thor feels. This, Midgard and Jane and his shield-brothers and -sisters, this is worth it.
If Natasha and Steve and Bucky have not aged a day, nobody says anything. There is an unspoken agreement. As long as it is not put to words, it is not real. Thor tries not to think that at least he has company in this slow torture. He would not wish this agony on anyone.
Tony is first. It all comes out after a mission, when he is sitting on a hospital bed in the Tower’s medical facilities. Tony has been getting increasingly reckless, and almost never returns from a mission unscathed anymore, even when the rest of them are not hurt. This is the first time it’s been bad enough for him to need a doctor, though, and Steve has had enough. He’s busy berating Tony when Tony says, “It doesn’t matter, though. None of it does.” He laughs once, a choked, humorless chuckle, and proceeds to tell them everything. “I have cancer.”
Thor doesn’t know what cancer is, but a single glance at the others in the room reveals it is nothing good. Tony refuses to look at anyone else, instead curling his shoulders in and staring at his hands. He is uncharacteristically still. Thor understands more when Tony quietly goes on, telling them that there is nothing anyone can do, and that he will likely be dead before the month is out. Unspoken is his desire not to die helplessly, to have some control over how his life ends. Thor can understand this, at least. There is honor to dying in battle which cannot be replaced.
Thor thinks of Eir, thinks surely she can fix this, and then remembers her words, “It is not our duty to interfere with the affairs of Midgard,” and knows that even if she can, she won’t.
Tony doesn’t leave his workshop after that. There are no missions, and few of them see him. Nobody knows what he is working on, except that it is important to him. Pepper brings him food, and when he can’t stand for exhaustion he falls into a fitful sleep on the couch he keeps for just that purpose. Two weeks later, no one is especially surprised when they find him there. On the floor beside him is a single sheet of paper lying on a folder labeled The Avengers. Thor sees the words I’m sorry, Pep , in Tony’s unmistakable scrawl, before he looks away. That letter is not his to read. Thor turns instead to the folder, which is full to bursting with schematics. There’s a new bow for Clint. Designs for stronger, smaller, lighter knives for Natasha. Guns. Comms. Better, more flexible body armor for Steve. Stretchier body armor for Bruce. There’s even plans for a phone that Tony believed would work on Asgard, so that Thor never has to be out of touch with his Midgardian friends. Tony designed something or improved on something for all of them, and each one of them knows that this was his goodbye.
Thor does not return to Asgard, but he thinks of Idunn and her golden apples. He remembers the bards singing about the first Asgardians, who ate sacred fruit and made their race immortal. Thor thinks, and he remembers, but he does not ask. He knows what the answer would be. “It is not our duty to interfere with the affairs of Midgard.”
Clint is next. They are on a mission in which everything goes wrong and Clint is left without backup and hopelessly outnumbered. Natasha finds him just as he falls, and it is there that she makes her own final stand. They find them, together, partners in life and partners in death. Natasha is lying half on top of Clint, entirely unharmed but for the single bullet hole through her temple. She could have walked away, Thor thinks. She could have walked away and instead she let them kill her. He cannot fault her for it, not when he thinks of Jane.
There is not a HYDRA agent who leaves that building alive.
There is no more death, not for a long while. Jane’s hair is showing gray at the temples when Thor returns to Asgard for the first time in decades. He has one request to make, and although he knows the answer before he asks he still has to try. His father stripped him of his immortality once, and he knows it can be done again. He is not surprised when he returns to Midgard, returns to his home, just as immortal as he was when he left.
He tries not to hate his father for it.
It is impossible to ignore the fact that Steve and Bucky are simply not ageing. By now, Bruce’s hair is more gray than brown, and Pepper’s is entirely white. Even the Hulk is showing signs of age, when one gets close enough, but Steve and Bucky are exactly the same as they ever were. The three of them often gravitate towards each other, in silent solidarity as they watch their friends slowly inch towards an end they cannot fight.
Bruce and Pepper both go before Jane. They are both older, and the stress of their lives has not done them any favors. Bruce takes longer and longer to recover from his times as the Hulk, until one day he simply does not recover at all. His death, at least, is peaceful. He falls asleep one night, and never wakes up. Thor can’t help but think that somewhere, Bruce and Tony are blowing things up in the lab again, only now Bruce doesn’t have to worry about hurting anyone if he is unexpectedly startled. Perhaps, somewhere, the Hulk is smashing to his heart’s content, and there is no one getting hurt and on one in his way. Tony would visit him, Thor thinks. Tony and Natasha and Clint, and the Hulk would be so happy to see his old teammates again.
No matter how he tries, Thor can’t make it any less painful.
By Pepper’s time, Jane’s hair is fully gray and her hands shake as she writes. When she and Thor go out in public, people tell her that she is lucky to have such an attentive grandson. They gave up trying to correct people, and instead she smiles and thanks them. She is still the most beautiful person Thor has ever seen.
When Pepper dies, Thor knows somehow that Jane is next. He only hopes that it will not be painful for her.
It takes years, years in which Thor watches as Jane slowly loses her control. Her science is beyond her now, because even when she wants to her hands are not steady enough to use the delicate equipment. Thor watches helplessly as frustration with her own body drives her to tears. He longs to go to Eir, knows that this could stop, but also knows that it would accomplish nothing. Even this many years later, he still remembers, “It is not our duty to interfere with the affairs of Midgard.” Something could be done, he knows, but he also knows that no matter what he does, nothing will change. He does not even try, this time. He will not waste the time he has with Jane.
Jane gets worse with every year that passes, and Thor knows that is is just a matter of time. She still talks, and she still makes him laugh and fascinates him with her never ending stories and her beautiful mind. He thinks that there can be nothing after this, that when Jane’s life ends, so too will his. She is, even weak and frail and old, the most beautiful woman in the universe, and Thor knows he will never find another to take her place.
When the end does come, Jane is too weak to stand. Thor holds her, and tells her that everything is going to be okay and as she breathes her last he kisses her. It is wet and the angle is wrong and she barely has the strength to respond and it is the worst and best kiss Thor has ever had. He does not know if the tears between them belong to him or to Jane, and he thinks that it hardly matters anyway. There is no shame in crying as a lover dies, and Jane was always so much more than that, anyway, even if Asgard never understood.
Her last words, on the exhale of her final breath, are “I love you,” so quietly spoken that no Midgardian could ever have heard them.
Thor invites Steve and Bucky to return to Asgard with him, even though he knows they will say no. They still have not aged a day, and Thor knows they never will. He doesn’t press them, just reminds them that if they ever wish to see him, Heimdall is always watching. He doesn’t expect them to take him up on his offer.
When he returns to Asgard, he is immediately pushed back into his life of being a prince, and he doesn’t fight it. He no longer has a reason to. By the time his father dies, his century as an earthly hero has mostly slipped the minds of Asgard as nothing more than an impetuous phase.
He never takes a wife, never has a child. There can be no one but Jane, never anyone but Jane.
Heimdall tells him when Steve and Bucky die. They stopped their train after more than three centuries of life, together ‘til the end of the line. Thor is not surprised to learn that Bucky and Steve went on a suicide mission to open the way for other agents to follow. Their deaths saved millions of lives, and Thor didn’t have to be there to know that they died exactly how they lived.
Thor leaves Asgard in the hands of Sif’s son. Sif would have been his queen had Thor never met Jane. He took the crown from her, Thor will not take it also from her son. Death is like sleeping, and Thor cannot help but be glad that he will not wake up. Now, at last, he will see his Jane again.
Bye Bye Baby Jane
I'm sure gonna miss the flowers in your hair
I'll see you again some day
But I don't know when and I don't know where
You were my first breath of sunshine, my first taste of rain
A million miles can't take that away