Unrelenting is a word used to describe someone who is persistent, determined and doesn't let up. If you are looking for an opposite or antonym of unrelenting, then you could use words like lenient, lax or easy-going. Words like responsive, adaptable, and cooperative also provide a way to describe someone who is the opposite of unrelenting. These are traits that would describe someone who is flexible, responsive to change, and likely to compromise when it is necessary. While unrelenting has a positive connotation in terms of work and persistence, its opposite describes a personality that is easy-going, open to suggestions and adaptable to situations.