Blending into something means to merge or integrate seamlessly with it, creating a cohesive and unified whole. Some synonyms for the phrase "blend into" are assimilate, integrate, merge, mingle, fuse, combine, unify, coalesce, harmonize, and synchronize. Each of these words suggests a slightly different connotation, but they all convey the sense of joining different entities together to form a unified whole. For example, you could talk about how two different colors blend together to create a new shade, or how someone from a different country might slowly assimilate into a new culture until they become indistinguishable from the locals.