When wanting to describe someone who easily conforms or adapts to a situation, it's important to have various synonyms to choose from. Some options for the phrase "fitting in with" include: blending in, assimilating, acclimating, conforming, integrating, and adjusting. Each of these words captures the idea of someone becoming part of a group or environment, and doing so in a way that is seamless and natural. Whether referring to a new job, a social group, or any other situation where fitting in is a necessity, being able to use different words allows for more creativity and precision in description.