In a 'Naruto Descendant of Ichigo' fanfiction, the plot could involve the descendant being born with a strange mark. This mark is a sign of their combined heritage. As they grow up, they start having dreams about Ichigo's battles and Naruto's adventures. These dreams guide them in learning new techniques. They could also face a villain who wants to steal their unique powers. To defeat this villain, they must learn to fuse the techniques of Naruto and Ichigo in ways that no one has ever seen before, and in the process, they bring a new era of peace to both worlds.
One possible plot could be that the descendant has the unique abilities of both Naruto and Ichigo. For example, they might be able to use chakra like Naruto to perform ninjutsu, but also have a Zanpakuto like Ichigo. The story could revolve around the descendant's journey to master these combined powers and protect their world from a new, powerful threat that requires both ninja skills and the power of a Soul Reaper.