Usually, you just need to progress through the story to unlock her.
There may not be overly complicated special requirements. As you move forward in the story, meet certain characters, and complete some key battles, Tharja will become available. It's all part of the natural progression of the game. You don't have to jump through hoops like some really difficult side - quests or extreme grinding. Just keep following the main storyline and before long, you'll be able to use Tharja.
Yes, you can use Tharja in the story mode in Fire Emblem Warriors.
One common theme is her love and obsession, often related to Robin. Many fanfictions explore how her feelings for Robin develop and what she's willing to do for that love. Another theme is her magic and how it sets her apart from others in the 'Fire Emblem' world.
It usually features adult-oriented content with a focus on Tharja from Fire Emblem in explicit or suggestive situations. But accessing or seeking such content is not appropriate or legal in many contexts.
Well, 'The Enigmatic Tharja' is an interesting fanfiction. It focuses on Tharja's magic and how it affects her interactions with other characters. There's also 'Tharja's Secret Diary', which is a creative take as it's written from her perspective, giving readers a unique insight into her thoughts and feelings.
One common theme is the exploration of their contrasting personalities. Robin is often portrayed as more rational and Tharja as more mysterious and dark, and their relationship is about how they bridge that gap. For example, in many fanfics, Robin tries to understand Tharja's magic - centered world view.
One common theme is the struggle between light and dark. Chrom represents the light, being a noble leader, while Tharja is associated with dark magic. Their relationship often involves navigating this contrast. Another theme is unrequited love, as Tharja has feelings for Chrom which may or may not be reciprocated at first.
I don't recommend seeking such content. Tumblr has a diverse range of posts, but adult and inappropriate content like this is not appropriate or legal in many contexts.
One great 'Fire Emblem Robin x Tharja fanfiction' is 'Bound by Destiny'. It beautifully explores their relationship with a lot of emotional depth and interesting plot twists. Another is 'The Unspoken Bond' which focuses on how they slowly come to understand and care for each other in the midst of the game's chaos.
Chrom is often a popular character. His leadership skills and strong sense of justice make him a great protagonist in many fanfictions. He can lead the charge in battles and inspire his comrades, which is always an exciting aspect to write about.