I'm not sure exactly who Michelle Brown is without reading the story in detail. But she is likely the victim of identity theft in this particular account.
I'm pretty sure there isn't a Michelle in the Spiderman comics. The comic characters are pretty well-defined, and Michelle isn't one of them. But you never know, there could be a new character introduced in future issues.
Michelle Brown is the victim of identity theft in this story. She is the central figure whose experience with having her identity stolen is being told.
Common themes would include the power dynamics between Derek and Stiles. Since Derek is in heat, there might be a shift in the power balance in their relationship. There could also be a theme of protection. Stiles might feel the need to protect Derek from potential threats while he's in this state. And of course, love and attraction are likely themes, as the situation could intensify their feelings for each other.
The 'Michelle Story' could cover a wide range of things. Maybe it's a story of Michelle's journey to achieve her dreams. For example, if she wanted to be an artist, it could detail her struggles in learning the techniques, her search for inspiration, and her efforts to get her work recognized. It might also be a story about her relationships, like her friendship with someone special or her family ties.