These boys are getting to be friends. Walter generally likes Dean and laughs at his antics. Dean likes Walt more than he used to, though he still often gets frustrated when I have to give Walt attention for feedings and what not.
One day Dean started saying "One, two, three, four hop!" and would jump. Walt thought it was hilarious. Ever since then Dean's really enjoyed trying to jump with Walter or make him laugh. Here's a video of them jumping together.