Annie is genuinely selfish, due to having been abandoned at birth and being used as a tool by everyone she has ever known, even by her adoptive father who wanted a better life for himself through her. She has no interest in protecting strangers due to being unattached to most of humanity to an absurdly high degree.
The main reason why Annie (and other rogue titan shape shifters) tried to kidnap Eren was to collect the potential candidates with the 'co-ordinate' power , i.e the power to control all other titans as slaves.
This is despite the fact that Annie acknowledges later being aware that leaving Armin alive would likely lead to him being able to use his wits to identify her as the Female Titan and thus potentially jeopardizing her mission. However, her growing feelings for him caused her to allow him to live.
After believing that Eren killed her father, Annie decided to not help her comrades stop him. She gave up all hope in the one goal that she had and never wanted to fight any of them, including Eren.
Annie was praised as impeccable for her fighting abilities and was later chosen as one of seven promising candidates to inherit the power of the Titans. She was later granted the power of the Female Titan in accordance with her stellar combat skills.
After these seventeen centuries when Karl Fritz, the 145th King of the Fritz family, abandoned the conflicts of Eldia and relocated to Paradis Island, the Female Titan was taken by the nation of Marley during the Great Titan War.
Annie was the main antagonist in the Female Titan arc, which took place in the second half of the anime's first season and volumes 5-8 of the manga. She did a lot of terrible things throughout the series, with most of them in that arc. Some fans consider her to be Attack on Titan's best villain.
In Eren's character interview, it is said that Eren has feelings for Annie; but doesn't know if it's out either romantic or just deep admiration. Isayama cleared this statement up and said it's only “deep respect.”
First, Annie had valuable information that they still wanted to get from her. It would make more sense to free her from the shell rather than to eat her. And second, it would make more sense for a different mindless Titan to eat her and gain her powers, like Armin did with Bertholdt, than for Eren to eat her.
When Eren was eaten and swallowed by the Bearded Titan, he found himself in its stomach along with the bodies of its victims. His rage at the Titans caused him to burst out of the Bearded Titan's stomach by transforming himself into the mysterious Titan and going on a rampage against them.
Not much is really known about Annie after her defeat, she has cried twice throughout the series (the second time is a spoiler) but from what evidence we can gather is that she saw that her mission was a failure and was saddened by it.
Bertolt and Annie were both Warriors from Marley, and Bertolt developed romantic feelings for Annie. It is unknown whether Annie knows about this. The two, along with Marcel and Reiner, are sent to Paradis to retake the Founding Titan.
The Female Titan is known for its high endurance and mobility, the greatest instance of this being when Annie Leonhart ran for an extended period of time during the 57th Scouting Mission outside the Walls with the goal of finding and capturing Eren Jaeger.
The last time we saw Annie Leonhart was when she enclosed herself in Titan crystallization after being defeated by Eren Yeager.
While Annie does show some hesitancy when it comes to killing her former comrades, she's still okay with killing others as long as it gets her closer to her believed goal. The only thing Annie truly wants is to be able to go back home to her father and live a normal life.
Annie would eventually become as strong as he wanted; but in retaliation for all she had endured, she attacked him and left him permanently crippled. The brutal training she endured left her callous towards others, unable to find any value in whether one lived or died.
Titan shifting power is transmitted by the consumption of spinal fluid. The Titan failed to drink eren and thus never became one of the 9 Titans.
Eren sacrificed his mother for a better future for the world. Eren reveals to Armin that he had a crucial role to play in his mother's death during their final conversation in Chapter 139.
Along with that, Eren seemed to be a special shifter. Where Reiner Braun, Bertholdt Hoover and Annie Leonhart inherited the powers of a single shifter, Eren had the powers of two shifters until Season 4, where he inherited another Titan's abilities.
Eren might not be the best at showing it, but deep down, he really does love Mikasa.
If there's one thing clear about Attack on Titan's Mikasa Ackerman, it is that she is devoted beyond all reason or logic to Eren Yaeger. For most of the story, it seems like her loyalty arises from the time he saved her when she was kidnapped as a child, but the latest plot developments imply some other force at play.
Bertolt Hoover
Bertolt has been in love with Annie since they were children, and both were Warriors from Marley alongside Reiner.
Levi managed to incapacitate the Female Titan, but at a crucial moment, the Female Titan summoned more Titans to come to her aid. As the horde of Titans joined, Levi impressively killed them instantly.
Dina Yeager, neé Fritz, also known as the Smiling Titan, is a supporting antagonist in the anime/manga series Attack on Titan. She serves as a major antagonist in the Prologue arc and as the final antagonist in the Clash of the Titans arc.
Can Eren beat Annie in hand to hand combat? If we're talking about just them without their titans, then no, it's been shown that Annie can yeet Eren. If we're talking about in their titan forms, then Eren would win. His Attack Titan is superior, as has been shown that Eren's titan can beat her.