When we first met Michonne on The Walking Dead, she had shut off her feelings and seemed more comfortable being alone. Since then, she's found her niche as a friend to people like Daryl and Carol, a lover and confidante to Rick, a surrogate mum to Carl, and the resident ass-kicker of the undead.
While she comes from a similar background as her character in the comics, the TV version of Michonne has taken on a much different trajectory. In the books, she loses two daughters to the zombie apocalypse; on the show, she loses a son, in addition to her boyfriend and friend. The most obvious change is her relationship with Rick. In the comics, they form a close friendship because of similar losses, but their relationship has remained platonic (though it's hinted that Michonne might have feelings for Rick). Instead, Michonne forms a significant romantic bond with Tyreese — before he becomes a zombie.
She also has an interesting relationship with King Ezekiel, albeit somewhat one-sided. While we hardly see them together on screen, the comics show them developing a strong trust with one another, eventually sleeping together one night. Despite Ezekiel's hopes for something more, Michonne clarifies that it meant nothing but could potentially lead to something else in the future.
After defeating Negan and finding some peace with Ezekiel at The Kingdom, she heads off on her own as chronicled in the interactive mini-series, The Walking Dead: Michonne. The three-episode series centres on her adventures on a boat and her eventual landing in a community called Monroe. When she returns, Rick asks her why she left and she explains that she abandoned her daughters during the outbreak therefore would never be able to start a new life living with such regret.
Heeding Rick's advice to get it together, Michonne returns home only to find that Carl has been kidnapped by a group called The Whisperers. They've also beheaded Ezekiel, leaving her distraught and seeking revenge. As a result, she gathers troops from the Hilltop in Alexandria to prepare for a war with this new threat, a war she eventually wins. However, the victors soon find themselves surrounded by walkers yet again.
That's all we know so far, and it'll be interesting to see how much of that makes it into the series!