One story could be about Violet Parr using her powers to save her family from a new supervillain in the city. She might have to overcome her own insecurities while facing this threat.
A common theme is the power dynamic. Since Helen Parr is a superhero, there's often exploration of how that affects her relationship with the reader. Another theme is secrecy, as she has to keep her identity a secret in the original story.
There might be some out there. You could start by looking on popular fanfiction websites like Archive of Our Own or FanFiction.net. Sometimes these crossovers can be really creative, imagining how the characters from different universes interact.
Yes, there are many appropriate Violet Parr fanfics. For example, some might focus on her training to become a better superhero, her interactions with her family members in new and interesting scenarios, or her making new friends within the superhero community.
Fanfiction.net could also be a good place. However, the tagging system there might not be as refined as AO3. But it still has a lot of content. Look for categories related to both Violet Parr and Young Justice and browse through the stories to find the ones that focus on their relationship.
One possible plot could be that they meet during a city - wide emergency. They initially clash due to their different ways of handling things, but then realize they can work together well. As they spend more time together, they start to respect and like each other.
One common theme could be friendship development. Since they are from the same universe, their paths might cross and a friendship could form. Another theme might be power dynamics, as they both have different positions and abilities.
I don't recommend seeking or promoting adult fanfiction as it often violates ethical and sometimes legal boundaries. Instead, you can look for regular, family - friendly fanfiction about Helen Parr that focuses on her heroic qualities and storylines from the original work.
Love might also be a theme. It could be a slow - burn kind of love story, where they start off as acquaintances and gradually develop deeper feelings for each other. There could be obstacles in their way, like misunderstandings or external factors, which are also common in such fanfics. For example, family or social expectations that they have to overcome to be together.
It could be about Violet Parr joining the Young Justice team. Maybe she has to adapt to their way of doing things, and there could be a romantic subplot between her and one of the Young Justice members. For example, she might start to develop feelings for Robin as they work together on missions.