Time Travel AU

Character A has time travel powers, had 'em for as long as they could remember, but they are VERY careful not to use them in big ways or risk altering history for the worse
They're pragmatic and don't see the worth in sticking their neck out for people even if it would save them because... People die, it's a fact of life, if they start going superhero whenever anybody's in trouble, who knows how that would end up fucking over the tides of fate?
So they get by through what basically amounts to ignoring the fact that they have any power at all and that's that
Then we have Character B
They're an average joe, completely unremarkable in terms of powers but remarkable in basically every other way, well-liked by their peers, athletic, smart, charismatic, financially well-off, and just a Genuinely Good Person all around
A and B have a chance encounter somewhere completely innocuous (but A isn't exactly sociable so they'd be hard-pressed to consider it an interaction)
Until
Character B dies, it's sudden, it's unexpected, and it might even be right in front of Character A
They don't understand it, can't wrap their head around why somebody who seems to have everything going for them could make a decision like that, and they get this itch
An itch they've never had before
Character A wants to find out-- needs to find out what drove B to do what they did
People die, it's a fact of life, but this is different
So for the first time, they use their powers for the benefit of somebody else
They go back to just before the incident and push that non-interaction into a desperate attempt to get B not to act on what they're thinking
And it works!
Sort of!
Except while they might have prevented Character B from going through with it that way, it ends up happening all over again a few days later
There's no erasing somebody feeling that low and hopeless in the span of a single conversation
Character A has to go back further and deal with the root of the problem, not just the eventual outcome
A isn't good with people and they try the direct approach, going up to B and saying, "Listen, don't do it, there's help out there for you," and B is understandably spooked and avoids any chance of A getting close to them again
One more time
This time, A tries being subtle, but B isn't going to take advice from somebody they barely know, so A needs to approach it from a different angle
Get to know them
They arrange a way for them to meet and establish a rapport and whenever they mess up in a big way, they go back to the beginning and try again
Little by little, they get closer and closer, uncover more things about Character B they had no idea would come in handy
Little things like routes home or favorite foods that they use to establish a bond early on
And the more practice they get, the more comfortable Character A is around B
The more A begins to like them
Originally, they went back because of curiosity, because they wanted to do something to prevent B from taking their life, but over time?
They keep going out of love
Things are going well
A and B are growing close, opening up to each other, and there's chemistry
This is the furthest Character A has ever gotten before and they are terrified
Elated, but terrified
Character B trusts them enough to let them in on their life and what's going on, things that are bothering them, pressuring them, putting too much stress on their shoulders, and this time, when Character A offers advice, they don't reject it
This is the first time B has had somebody who seems to understand so intimately without judging them
So they agree to talk to other people about their issues, get help, and move forward
It's on one unremarkable night when, as young adults are wont to do, they end up getting drunk and A, a total lightweight, passes out immediately, leaving chronically responsible B to carry them home
Not such a big deal, nothing they've never done before, but all the times B has visited A's place, it's always been pre-planned, giving Character A time to prepare and make sure that there are certain necessary things out of sight by the time B arrives
Because!
It turns out Character A kept notes
Details of different timelines, big milestones, little tidbits of information they didn't want to forget-- In their defense, it is a bitch trying to keep all these different timelines straight and their memory can only stretch so far
They've filled journal after journal full of sketches, charts, differences in outcomes and theories on which decision leads to what result
Character B, after laying B down on their bed, spots one of these journals left open and despite themselves, because they are not a perfect human being whatever A believes of them, they're curious
They flip it open and discover things about themself that character A-- their Character A, at any rate, couldn't possibly know
Childhood stories B has never told them, scars in places A has never seen, notes about scary things like their route home, and featured so many times, the different circumstances of B's own deaths
Some are accidents
Some are intentional
B is understandably shaken, questioning what they really know about Character A
And decide that the only way they're going to get any answers is to wait until A wakes up
A wakes, disoriented and confused, to B sitting by their bedside, with one of their important journals in their hands, and freaks the fuck out
"Where did you get that?"
"You left it sitting out."
"You went through my things?"
"Compared to what you've got written down in here, you've got some balls to accuse me of invading privacy. If this is some sick joke or weird attempt at friendfiction, it was a nice attempt, but it's not funny."
Character A could lie
They could run away
They could reset so that none of this ever happened
But keeping all of this bottled up has been tearing them up inside, and this is the first time they have ever gotten so far. Things were going to be better. They had plans. They were finally making a difference. So if it was fate that Character B found their journal, then maybe it was fate that Character A come clean
About everything
B is quiet while A tells their story, and only speaks up once they get close to the end to ask the one thing that both of them were trying to figure out
"Why do this? Why me specifically? I couldn't have been the first person whose death you might have prevented, so why try so hard for somebody you didn't even know?"
Character A thinks on this for a long while before they shrug and get this hapless smile on their face. "I don't know myself. I just felt like you were more important than you or I assumed before. And now that I do know you, I figured out I was right."
This clearly hits Character B like a ton of bricks, but they're having a hard time wrapping their head around it, so they ask A to prove it, tell them something that nobody else knows, so A couldn't have heard it from asking a friend or relative.
A knows that answering this hinges on whether B will believe them, and if they mess up, there's no chance of salvaging this time
So they take a deep breath, look B square in the eye, and tell them, "The first time you were planning to kill yourself, it would be at a train station on your dad's birthday."
And that was that
Nobody else could have told Character A that, B wouldn't even be the one to tell Character A that
The only way they could possibly know that is if they had been there, if they had seen it, if they knew of a time where B was successful
So what is there to do at that point but believe them?
B needs some time to think, A needs some time to freak out, so B goes back home to sleep on what they've learned
They don't talk for a week
A is a spring wound too tight but they refuse to be the one to approach B before they're ready
They leave it up to B to approach them, and if they never do, then A will know it's time to reset
But they do
Finally
And all B asks when they finally approach A is, "What can I do to make sure you never have to go through jumping through time again?"
"Just keep yourself safe and don't feel like you need to handle everything on your own."
"Why would I? I've got you looking out for me, don't I?"
AAAAAAAAAAAND SCENE
Thanks for coming, everybody, that was a great job we did out there