A great fanfiction is 'When Thor Met Black Widow'. This one is set in an alternate universe where the Avengers have different dynamics. It shows how Thor and Black Widow might interact and form a bond outside of the normal storyline, with some exciting action scenes and emotional exchanges.
There's a fanfiction titled 'Black Widow's Encounter with Thor'. In this story, they meet in a different setting than the movies and their interactions lead to some interesting character developments. It delves into how their different personalities clash and complement each other.
One popular black widow and thor fanfiction is 'Thor and Black Widow: An Unexpected Alliance'. It explores their relationship in a unique way as they team up for a mission.