is one piece episode 686 filler?

The fighters below notice that Pica's stone body has frozen, and take advantage of this to head for Doflamingo's castle, intent on his head. Luffy, Abdullah, and Jeet continue riding away from Pica, the latter two refusing to get off despite Luffy's demands.

Suddenly, Law snaps out of his thought, admitting to Luffy that his plan had been a detour to crush Doflamingo, but that he, too, wanted to repay the Shichibukai after losing to him before. He then tells Luffy how Doflamingo took away the most important person to him 13 years ago.