It's not like it didn't occur to me that Claire and Jack would have recognized each other on the island. But one of the reasons the writing on Lost can get so bad is that they are always revisiting old events and changing what happened, or showing what happened just out of the frame, or right after the scene cut when we first saw it (or worst of all, they'll add elements to original shots, such as Nikki and Paolo at the crash site).

If the writers suddenly want to show us flashbacks where Jack and Claire were having private discussions on the island, they will. Lost characters hardly ever act rationally; they act in a way that is convenient to where the writers want the story to go. They have claimed that they had the story mapped out from the very beginning, but it seems pretty obvious to me that things have been added along the way. Things don't always fit, but these guys work under the "make it fit" philosophy, so it doesn't really matter. Force it into the story. Bend logic, change the past, it's all part of the show and what it's become. In exchange for making things interesting, they've made things complicated. Every time a character dies, the writers feel the need to introduce two new characters. For every old question answered, there are five new ones asked. Some mysteries fade into the background because they never had a purpose other than to thrill the audience for a brief moment.

Do I seriously think Jack or Christian may be baby Aaron's father? Probably not, but I'm just saying the baby looked like it had a touch of downs, and Claire wanted to give it up for adoption before it was born. Just a thought that I haven't heard anybody mention yet. And the writers obviously don't work under any rules. That's the beauty of their island. Anything goes.