@Grey WolfI too will recommend the Variation on a Theme series! Well written, both in terms of engaging plots, and writing style, humor and drama, as well as spelling, grammar, and other technical aspects.
Without giving away specifics, many chapters into the story an incident occurs in the story (that Anyone from Our Timeline) that is not consistent with the history we know... Not something changed by the Character(s). It gave me a different Perspective on this series. Unlike similar series, the Character(s) cannot be certain that investments, or other things they attempt will be successful based upon "Knowledge of the Future"...
In many similar stories, readers can presume that the MC will certainly be successful, because we KNOW how things turn out.
Also, I appreciate the consideration of the MC(s) to try to never "steal" from others by doing something another person will (likely) do in the future.
Grey Wolf and I have some very different opinions on some matters, mostly matters of politics and/or social matters. That said I very much enjoy his story. Any "political issues" from matters of a local school board, to opinions (and actions) with national effect are depicted well, and such that a person who might disagree with them would have to admit are consistent to the Character(s). Politics and social matters are key elements of this story; but depicted in a manner that (I think) most people would enjoy. Such matters develop as part of the story. To be clear, politics are absent from most of the story.
Not everything in this story occurs in a manner favorable to the MC (or other characters). Despite being clever as well as smart, and having foreknowledge, they don't always succeed. Often the characters have to opt for "smaller" victories and "lesser evils" making times when they achieve a major success even sweeter! Too often in these types of stories, everything the MC does is a Huge Success.
This is my favorite series. If it continues the way it has, I would enjoy reading about the entirety of these characters potentially very long lives.