Since I don't know the 'amy love story', I can't say who the main characters are. It could be Amy herself and someone she has a romantic relationship with, but that's just speculation.
Sonic might be really confused if he is under the effect of the love potion. He's always been independent and suddenly having strong romantic feelings for Amy would be a big change. He might try to fight the feeling at first because it's so alien to him.
Well, it could be that Amy and Matthew started as friends. Maybe they were classmates or worked together. As time passed, they realized that their friendship was turning into something more. There might be some sweet moments like sharing secrets, going for long walks together. And through all these experiences, love blossomed between them in 'amy and matthew a love story'.
Amy Rose shows her love by constantly chasing Sonic. She is always by his side during his adventures, ready to help. For example, she'll bring him a meal or offer to patch up his wounds.
You can find them on fanfiction websites like Archive of Our Own (AO3). It has a large collection of Sonic - related fanfictions, including those about Shadow and Amy's love. Just use the search bar and type in relevant keywords.
You can try some popular fanfiction websites like FanFiction.net. There are a large number of Sonic - related fanfics there, including ones about Shadow and Amy's love story. Just use the search bar and type in 'Shadow and Amy love fanfic' and it should bring up relevant results.
Some Sonic - themed forums may also have user - shared fanfictions about Knuckles and Amy's love story. You can engage with the community there and discover some unique and interesting works.
One challenge could be the difference in their personalities. Shadow is often cold and distant, while Amy is warm and affectionate. This might lead to misunderstandings, like when Amy tries to show her love in a big way but Shadow misinterprets it as being too pushy. Another challenge is how their friends might react. Sonic and his friends might be a bit surprised by their relationship and it could take time for everyone to accept it.