Noble, Loving, Trusting
At the beginning of the play he is motivated by his hate of Beatrice. He hates her because he was dumped by Beatrice. Later in the play, Benedick is motivated by friends and love. When Claudio, Don Pedro, and Leonato were talking about Beatrice out loud he believed every word: "This can be not trick. The conference sadly borne;...".(pg. 77 act 2 sc.3). He was shocked by what he heard and thought it was impossible but believed it still. He still loved Beatrice so he wanted to believe it even further. "I will be horribly in love with her." (pg. 77 act 2 sc.3).
In the beginning Benedick hated love he didn't seem like it was needed. "With anger, with sickness, or with hunger, my lord, but not with love... I will die a bachelor" (pg. 21 act 1 sc.1). All his friends thought that he needed to remember how to love. So they made a plan and tricked him into believing that Beatrice loves him. So he falls for it and starts falls in love with Beatrice once again. "When I said I shall die a bachelor, I did not think I should live till I were married!"(pg. 77 act2. sc.3). His friends knew that their trick worked and they were happy with the results because they also tricked Beatrice into thinking that Benedick loves her. At the end they got married because they both were finally were in love.
Impacting the theme
Benedick impacts the theme by being the "anti-love guy" in the beginning then becoming the "boot of a joke" in the middle. He also gives the biggest change in the whole book by going from a anti-love to a married man.