Ok now while I find this alternate time line or as most fan's call them "Flash Sideways", to be confusing and a waste of space, this episode really showed the up's of this.
I thought at first that these Flash Sideways were just to show the audiance how much the charecters lives would suck if they didn't crash on the island, But it also stands to reason that other things in their lives would be differnt do to the whole time line ripple effect that we've seen in so many time travel movies. But here we get a big change as well as some charecter development which is common among charectersaproching the series final.
This is a Jack centric episode, but we seethe whole Shephard family playing big roles in this episode, on the island and in the Flash Sideways as well.
I'll start with Claire Littleton who we haven't seen for a whole season (not even in Flash backs), and to sum up whats happen to her infew words. "SHE CRAZY" and a threat to the Others and survivors (Espeacially Kaite). but I got say she plays a great psyco and it's interesting to see her as the polar opposite as her usual charecter role (the sweet young Austrailan mother). This also makes me want to see a Jack Claire sibbling moment (Of course I've been wanting that since season 3).
Hurrly convices Jack to leave the creepy Other temple and go to this lighthouse that they never knew was on the island which is conviently close to their camp bythe cave.
The lighthouse has a wheel with names and numbers, Jack finds his name and spins the wheel and see's the house he grew up in, this causes him to freak out (a normal reaction to learning someone's been watching you years since you were a kid) and Jack Bracks the lighthouse. This is what Jackob wanted so that Jack can start realizing that he has purpose. (Also the Other's Temple is about to be under attack and Jackeob didn't want Jack and Hugo to die)
In the flash sidways, we find out that Jack had a Teenaged son named DAVID SHEPHARD in this alternate reality. now i know Jack was married at one point but given Davids age I don't think it was with that women.
The Shephard family (minus Claire) are dealing with the after math of Christan Shephard's Funneral (that was without Christan's body) Jack and his mom look for his will and they disscus the "father son Shephard relationship curse" that he and David are going throw, just like what Jack and his father Christian went throw and what Christian and Ray went throw.
They find the will and Claire Littleton is mettioned, this forshadows a metting between the two in another Flash Sideways, one i look farward to (altough Jack's mom may not)
when Jack comes home he find's Daivd is gone so Jack serches for him frantecly. his search leads him to Daivd school where he is preforming in the auditorium for a piano resital, Which he did not tell his dad about.
Jack confrots David as leaves the school and have a heart to heart talk. According to Jack, David stopped playing the piano after he and wife divorced but David continued to practice but made his mom sware not to tell his dad, the reason for this is not because he thought he dad would disapprove of his hobbie but rather David was afraid of failing or disapointing his father because he couldn't play a song right.
Jack Tell's David that in his eye's he could never fail, they have moment then drive home breaking the father son Shephard relationship curse.
This is one of those last season episodes that make you think back to the first season and see the main charecters (that are still in the show) over come their personal deamons and progress. Jack's main demon has been his own father and struggling with making the right choices and making apemds for his mistakes. This episode truly show's Jack's Resolve, now the island has it's leader back!