Hermione Granger from the Harry Potter series is quite popular. Her intelligence and strong personality make her an interesting character to write in fanfictions with a female reader. Another one is Katniss Everdeen from The Hunger Games. Her courage and leadership skills are often explored in these types of fanfictions.
Lara Croft from the Tomb Raider series is often used. Her adventurous spirit and physical prowess are great elements for female characters x female reader fanfiction. Also, characters from Disney movies like Elsa from Frozen can be popular choices. Her struggle with her powers and her journey of self - discovery can be beautifully intertwined with a female reader's story in fanfiction, creating some really engaging and heart - warming stories.
Clockwork is also quite popular. With her unique appearance, half - clockwork face, she can bring a sense of mystery to the relationship with a male reader. Fanfictions might explore how the male reader reacts to her different - from - normal looks and her somewhat unpredictable nature.
Rukia Kuchiki is a very popular choice. She is one of the main characters in Bleach and has a strong personality. Her relationship with the male reader in fanfiction can range from friendship to romance, given her complex character and the various storylines that can be created around her.
Charlie is often paired with the male reader. Since she is the princess of Hell and the owner of the Hazbin Hotel, she has a big heart and is always looking for redemption. The male reader might be drawn to her positive attitude in such a negative place. Their relationship could develop as they work together to try and rehabilitate the sinners in the hotel.
Joker is often paired with the female protagonist. Their relationship can be explored in different ways, from being comrades in the Phantom Thieves to having a more romantic connection. Ryuji is also a popular choice as they can have a fun, energetic dynamic.
Sakura is often paired with the female Kyuubi in some fanfictions. Her strong - willed nature might complement the powerful female Kyuubi.
Fanfiction.net might also be a good place to look. However, the tagging system there isn't as refined as AO3. But if you use the search function and look for relevant key words related to the female characters and the 'female reader' aspect, you may find some interesting stories. Some Tumblr blogs also share and recommend such fanfictions, so you could search for relevant tags there as well.
The Medic can also be paired with the female spy in fanfiction. The Medic's ability to heal and the spy's ability to infiltrate can make for some great stories. For instance, the spy might be on a mission where she gets injured and has to rely on the Medic to patch her up while still keeping their location a secret from the enemy. This creates a lot of tension and opportunities for character development in the fanfiction.
Elizabeth Bennet is extremely popular. Her strong - willed and intelligent nature makes her a great character to put in new and different situations in fanfiction.
Gengar is a popular choice. Its already spooky appearance and ghost - type nature make it easy to incorporate into horror scenarios. It can lurk in the shadows, play tricks on trainers, or even possess other Pokemon to cause chaos.
Christian Grey from 'Fifty Shades of Grey' is often used. His character is very possessive and has alpha male traits. Another one could be Edward Cullen from 'Twilight'. He's protective and possessive of Bella, showing alpha male qualities in his relationship with her.