This wasn't originally planned, but Charlie just blew me away, so... here it is.
LadyAwesome45321: I had the exact same feeling about Ava! And I had the same thing about Charlie, too, but she's started to grow on me (though I wouldn't rule out betrayal at this point). Thanks for reviewing!
Shifter
After defeating the demon Neron, John and Charlie left the Waverider. John left because the demon was the only thing keeping him on the ship and Charlie left because she wanted to see the world a bit. Neron had given her powers back to her prior to his defeat, which would enable her to explore the world without consequences. She'd miss the Legends, but at least she was allowed to stay on Earth and at least they did not send her back to hell.
As she traveled the world, she regularly shifted into Amaya again. It was the closest thing she had to an own face and an own look. Of course, the style never changed, but the appearance always did. It was comforting to return to this one familiarity in her life.
During her travels, she encountered another group of shapeshifters. They had managed to stay under the radar after their escape by not doing anything outlandish, and Charlie was quick to join them. she was blinded by the fact that she finally found some brothers and sisters with the same powers that she did not stop them.
This group had an affinity for causing trouble at key moments in modern history. These were the kind of moments the Legends could not fix immediately, lest the future would be radically changed for either the better or the worse; more often than not, it was the worse. Charlie opposed them at first, but they managed to convince her that this wasn't going to be harmful, but that they were going to "fix the future". She believed them.
They did fix the future. They dethroned a dictator and eradicated hunger in the Middle East, among others. Unfortunately, another dictator came to power – one who was worse than the other and better at masking his true intentions – and with people not dying of hunger anymore, the Middle East (and the entire world, really) had a small problem with overpopulation. At the moment, however, these choices seemed smart and desirable, but they threw the future off-track. The first dictator would have been dethroned sixteen years down the road and the country would have become democratic again. The hunger would have killed millions, sure, but there would be enough space for the survivors to live in and that community would be considerably less violent.
All of those consequences Charlie could have thought of but didn't consider because she was so swept up in the group of shapeshifters. All consequences that drew attention to her as a shapeshifter, because the future kept being changed by random seemingly unconnected people in the same relatively short time span.
Charlie helped her newfound family to evade the Legends. She herself sought to talk with the Legends, to explain their motive. The Legends wouldn't listen and told her she was doing some serious damage to time. She kept them off of her new friends' back for a long time and then fled herself. That was the last time she spoke with the Legends.
That was not the last time she saw them. The Legends had taken up the job of protecting the timeline and major events, some of which the shapeshifters wanted to change. They did not quit in their quest but decided to lay low for a while.
Charlie did not remember why she left them. There must have been a disagreement. They may have tried to kill her. She should have kept it to herself that, after spending fifty years with them and finally – slowly – feeling the consequences of their actions, she agreed with the Legends. The shapeshifters don't like to hear that one of their own is siding with the group that is actively trying to prevent them from changing the world for the better.
Either way, Charlie died in anonymity in a small apartment in New York City, 2106, having lived to the ripe old age of 139. There wasn't a body she shifted into that could save her from an untimely heart attack. in the meantime, the world had continued to change drastically. The closest description of the society that day was a dystopia heavily disguised as a utopia; nobody minded the current situation, but they all knew something was off. And Charlie regretted meeting the shapeshifters, and she regretted changing the future with them.
But it was too late. She could not change what has passed and history, especially the Legends and the Time Bureau, would remember her as someone with malicious intent, someone who was actively trying to create a bad future. And she could not change that, however much she wanted.