In the comics, Yelena doesn't kill Clint. Their relationship is complex but not marked by such a violent act. There are various conflicts and resolutions, but not this one.
One great Kate Bishop and Yelena fanfic is 'Partners in Crime'. It has a really engaging plot where they team up for a mission. The author does a wonderful job of writing their interactions, full of snappy dialogue and a growing bond between them.
Well, 'kate and yelena fanfiction' like 'Shared Secrets' is really good. It delves into their backstories and shows how those past experiences bring them closer. Also, 'Journey Together' is a story that takes them on an adventure and along the way, their relationship evolves in a very engaging way.