Disclaimer: If you recognise it, it came from the films or the comics, even if I flatter myself that I've put my own spin on things.
Feedback: All constructive comments or appreciative observations are welcome
AN: This fic opens around the beginning of Avengers: Endgame, but it will soon become apparent that a particular details has changed from canon, which will snowball into the wider changes.
AN 2: To clarify one detail about the name of this fic, 'The First and the Last' refers to Carol being the first official Avenger while Peter was the last. I appreciate that Steve was Earth's first superhero in the MCU's timeline, but his status as the 'first Avenger' was only retroactively applied once he was found in the ice and revived by SHIELD, since before then everyone believed Steve was dead (Peter is the 'last' Avenger as Tony unofficially inducted him into the team during the flight to Titan).
AN 3: In advance, this fic will include a relationship developing between Peter Parker and Carol Danvers, and some sexual scenes will be featured as a result. I can assure you that nothing will happen before Peter becomes legal, the plot will still be the central focus even if their changed dynamic will also be important, and I will amend the rating as appropriate when the time comes, but I thought I should give you advance notice.
AN 4: On a related note, be assured that I am aware of certain related revelations regarding the Skrulls in Secret Invasion, but until we have more established facts I will be operating on the premise that certain things that were only disclosed by the producers rather than confirmed in-series don't apply (if things change later on I will adjust my plans accordingly). If you've seen the show, you can probably guess what I'm talking about; if you haven't, just know that I'm aware of the overall plot and just have a couple of personal opinions I'm adhering to until we know more.
AN 5: Since I originally posted this fic I have made a few edits to early chapters based on revelations in The Marvels, but the overall plot remains unchanged.
The First and the Last
The strangest thing about returning to Earth was that Carol hadn't been particularly affected by it.
Most of her memories had returned over time since she'd removed that implant and allowed herself to indulge when she had a moment to spare, but she'd never really let herself think too much about it. She was grateful to Maria and Monica for accepting her back into their lives so easily, and she had appreciated Fury's support during everything that had happened, but when she got caught up in exploring the possibilities of her new wider responsibilities…
Well, she'd always wanted to go far and get away from her controlling family; this just made it easier for her to do that. The need to protect her homeworld from the consequences of her killing the Supreme Intelligence had been a factor, but after a certain point that excuse didn't really work any more. The civil war might have been horrible, but it basically compromised the Kree's ability to mount any kind of large-scale assault on Earth, particularly when they were still focused on hunting for the Skrull refugees.
Carol would like to believe that she had managed to take advantage of the situation to help the Skrulls find new homes, but even with the war leading to the Kree abandoning some of their colonies, they only had so many options. Even with Talos to vouch for her it was hard for a race that had been in hiding for so long to just turn off their suspicions when faced with someone offering to help. She had done her best to drive off Kree expeditionary forces into certain parts of space to make it clear that those areas would be off-limits, and a few old Kree colonies could serve as at least a staging post, but she always knew that wouldn't be good enough long-term. The Skrulls needed somewhere to stay on a relatively larger scale, rather than hiding in random planets where small groups of them could hold on to whatever parts of their culture remained in secret. Reclaiming Kree colonies gave them a defensive position, but what most Skrulls really wanted was to find their own planet to live in peace out of the way of the Kree Empire. Either any suitable planet already had people living on it, or there was some reason why an uninhabited planet couldn't be occupied, from it being too close to potential enemy territory to there being some detail that made it unsuitable for colonisation.
Even when Carol moved beyond the borders of the Kree Empire to continue her search, there was no way to guarantee that the Skrulls' territory would stay hidden from the Kree if they ever expanded further, or that the other empires wouldn't have some objection to their presence. She had earned favours by saving a few planets during her travels, and had even toppled a few of the more corrupt rulers she had found in the process, but she had never been sure that these new rulers would stay in power long enough to make her friends feel safe.
In a dark way, the Snap seemed a rare opportunity to face a relatively simple situation that had nothing to do with her wider campaigns, as everyone she encountered had agreed that this was a horrible act carried out by a madman with extremely warped ambitions. Even the remaining Kree wouldn't be much of an issue; whatever the impact of the Snap on their civil war, they'd currently be focused on rebuilding their own forces over pursuing any new campaigns. The scale of the Snap was terrible, but at least she could say with absolute certainty that everyone involved hated what had happened. She almost hadn't believed it when she first met the heroes of Earth and learned what had been responsible for so much death, but hearing more about the nature of the Tesseract had at least given her some context for the power involved in such a feat.
But at the same time… maybe it was selfish, but the idea that she'd made such an impression on Fury that he'd named his plans to create a superhuman defence force for Earth after her… after the way she'd messed up on Hala, it was nice to have some sign that she had done the right thing elsewhere…
Carol shook that thought off, getting her mind back on the reason why she was currently flying through space rather than back on Earth. Right now, with their most obvious leads on Thanos essentially exhausted, the best any of them could do was to gather all their resources together and hope that they could find a new approach. The racoon (and she really wondered how that had happened) had been able to study the readings obtained by Earth's satellites when Thanos had launched his first attack on New York. Once he had confirmed the direction taken by the attacking ship after it left the atmosphere, Rocket had offer the theory that it had been heading for Thanos's old homeworld. With no better ideas, Carol had set off at her best speed to follow the most direct path to that planet, once again grateful for her experience travelling at near-lightspeed. She could have covered the distance to that planet in a matter of hours if she was going all-out, but if there were any potential survivors of Thanos's own attack, they had to assume they'd be using that ship to get back to Earth, which meant that she had to maintain a slower speed that allowed her to be aware of what was happening around her in case it passed her by.
She'd already lost a few days on the way back to Earth as she'd taken detours to do what she could for other Snap-affected planets on her route, but now she only had one goal; if anyone had survived on Titan and managed to find a way off, she had to find them and bring them home. The racoon had mentioned that his own team would have probably tried to intercept Thanos on the planet, so there was at least likely to be a working ship for any survivors, but that depended on too many questions like what state the ship had been in or who else had survived whatever Thanos did there to get his hands on the Time Stone.
Carol wasn't sure how long she had been flying before she finally found the ship, drifting in deep space on low power, the engine clearly off and the ship itself barely illuminated. The racoon's description had at least been distinctive, but if she hadn't been actively looking for something like this she was certain she would have missed it. From what she could see, the ship seemed to be reasonably intact, so it must have at least been able to take off from Titan after the battle against Thanos, but that still left the question of who was still on board…
"H-hello?" a voice said over the radio earpiece the Avengers had given her back on Earth. "A-are you… is this real?"
"Hello," Carol said, reaching up to activate her own radio. "You're in this ship, right?"
"Y-yeah," the voice said, as Carol dimmed her energies to let her better see through the glass at the front. The dimmed light revealed a young man crouching near the pilot's seat, wearing a metallic red-and-blue suit with gold highlights, looking a bit thin and pale but otherwise in good shape for a human of his age. "I-I'm Spider-Man… Peter Parker."
"Hey, Peter Parker," Carol smiled at the young man, giving him a reassuring smile. "I think I'm here to help you."
It was a small step, but she definitely remembered that one of the people who had been on the ship when it left Earth went by the code-name 'Spider-Man', so at least she knew that she could bring one person back to Earth to see her new allies…
AN 6: And there is the change; Peter Parker survived the Snap instead of Tony Stark, even if everyone else who survived or dusted is basically the same as in canon (obviously for those where we don't know for certain if they were or weren't Snapped, I'll be making my own choices).