You might want to check out 'Harry's True Love'. In this fanfic, Harry picks Luna Lovegood as his mate. The story explores their unique connection and how it evolves over time.
I'm not sure I've come across such a specific fanfic. Maybe you could try looking on some popular fanfiction websites and using relevant search terms.
He might be initially in shock. Harry could stand there, unable to believe what has just happened. Then he might become angry, lashing out at his mate or the situation in general. He could say things he doesn't really mean in the heat of the moment.
It can change the narrative by adding a new support system for Harry. Instead of just relying on his friends, he has Remus in a more intimate 'mate' role. This could lead to different plot developments, like Harry making decisions based on Remus' advice more often.
It can add an interesting dynamic. For instance, it can create a power imbalance that drives the conflict or resolution. If Harry is submissive, other characters might take advantage of him, leading to a plot where he has to overcome this exploitation.
You must be a Horcrux, because you've got a piece of my heart.
In fanfic, Harry as a submissive mate could be characterized by his self - sacrificing behavior. He may be the type to endure hardships or put himself in difficult situations for the sake of his partner. His emotions might be more openly expressed in a vulnerable way, like being more likely to cry or show extreme happiness in the presence of his partner. This submissive role can also make him more receptive to change and growth within the relationship, as he is more open to his partner's influence.
I'm not sure if it's a popular fanfic concept. There are so many different types of fanfics out there. While the idea of Harry Potter being Voldemort's mate is very different from the original story, it might attract some readers who are looking for something completely new and unexpected. But it could also turn off a lot of fans who prefer to stick to the more traditional interpretations of the characters.
You're more alluring than the Philosopher's Stone.
Harry might be deeply hurt. He may initially be in denial, not believing that Severus is rejecting him. After all, he may have felt a strong connection. So, he could try to reach out to Severus multiple times, hoping to change his mind.
He might be initially heartbroken. Harry has always been a bit of an emotional person, so he could go into a state of depression for a while. He might isolate himself from his friends and focus only on his studies or fighting against the dark forces, using it as a way to distract himself from the pain of the rejection.