The adage in The Walking Dead universe is that if you don't see a body, the person isn't dead and is likely appear again, if the writers have already invested some time with the character. When we last saw Daniel, it was last season and he appeared to be lost in the fire at the commune which scattered the cast. It was easy to believe that Daniel had perished given the ferociousness of the fire but then - we didn't see a body.
Daniel popped back up in the beginning of this season, a possible ally to Strand, who found that his familiar charm had fallen flat. Now that the audience knows that Daniel is alive, the writers must explain exactly where he has been all of this time and how he has survived. Though this explanation is necessary to reintegrate Daniel into the series, a lot of what happened felt like filler. Having a filler episode in only the third episode of the season does not bode well.
One of the defining features of Daniel's character is his guilt. It's clear that in the course of his life that he has killed many men in the service of his government at the behest of the US government. He may have been a retired killer turned barber when Travis met him, but he was perhaps better suited for a zombie apocalypse than any other character. Everyone else had to adjust to what it means to kill for survival and fight for their life, whereas; for Daniel this experience brought about flashbacks. His break down if anything was a sign of untreated trauma and PTSD. It's why he fell apart while the others were able to simply shoulder on with surviving in this hard new world.
Daniel has always had the skills but burdened with the memories of what he has done, his hands are already so soaked in blood that this new world in which killing is no longer problematic simply drove him over the edge. Despite everything that Daniel has done however, it seems that the universe (read: the writers) are determined that Daniel survive. Daniel is first saved by a dog when a zombie tries to bite him and then by Efrian, who gives him water and gets Daniel medical treatment for his badly burned leg. Efrain and Daniel form a duo for a time, scrounging for supplies and giving mercy to walkers.
Daniel ends up in a much better mental place then when he burned down the compound; however, he still thinks about what he did and worries about the fact that he and Ofelia are seperated. Finally, when Daniel can no longer hide from what he has done and filled with worry for his daughter, he decides to confess to Efrian.
Daniel makes his way away from Efrain on foot but when he comes up against a zombie, with no weapon to protect himself, Daniel falls to his knees and begins to pray. Instead of being eaten, he is knocked unconscious when the zombie is struck in the head by lightening. While it was an awesome scene, I couldn't help but think that the writers were laying on Daniel's temporary plot armor a little to thick. It's like they decided to do the lightening strike simply because this is something they always wanted to do and thought it would look cool.