One common theme is self - acceptance. Alex has to accept herself first before coming out to others. Another theme is the support from family and friends. Often in these fanfics, Kara plays an important role in supporting Alex.
One popular 'Alex Danvers coming out fanfic' is 'Finding Herself'. It beautifully portrays Alex's journey of self - discovery and coming out. Another great one is 'Out in the Open' which focuses on her interactions with her friends and family during this process.
I'd recommend 'The Danvers Sisters' Journey'. It focuses on their growth as individuals and as sisters. It has some really heartwarming moments, like when they have late - night talks and share their deepest fears. It also shows how they deal with the villains in their own unique ways, all while strengthening their relationship.
One possible fanfic could focus on a mission gone wrong that leads to both Alex and Kara experiencing PTSD. In the story, they might initially try to hide their symptoms from each other. Kara could be having nightmares about not being able to save the people she loves during the mission, while Alex might be jumpy and overly vigilant. As the story progresses, they finally open up to each other and start to heal together, perhaps through some shared training sessions that also double as therapy, where they learn to trust themselves and each other again.
A good 'Alex Danvers and Kara Danvers Fanfic' has to capture their unique relationship. Since they are sisters, it should show the love, bickering, and support that comes with that. For example, if it has a scene where Alex is training Kara and is tough on her but also encourages her, that's great.
I'm not sure specifically about 'omega thrasing' fanfiction involving Alex Danvers. You could try searching on popular fanfiction websites like Archive of Our Own. They have a vast collection of Supergirl - related fanfics and might have something that fits this criteria.
Another theme is the idea of finding one's place. Ruby, being a young character, is often on a journey to figure out where she belongs in the world. And Alex, with her own experiences, helps Ruby in this quest. In some fanfics, this is shown through Ruby joining Alex in her superhero activities and realizing that's where she wants to be.
One possible fanfic could focus on how they support each other through their PTSD episodes. Alex, with her military background, might have PTSD from combat situations. Kara, having lost her planet and family, also has her own traumas. They could share their nightmares and fears, and use their superpowers in non - physical ways to comfort each other, like Kara using her heat vision to create a warm and calming environment when Alex is having a flashback.
Often, Alex Danvers is portrayed as the strong, silent type who is fiercely protective. In fanfic, she might be shown as being a bit guarded at first when interacting with Cat Grant. For example, she may be suspicious of Cat's motives in a story where they first meet.