The past two episodes of Stargate Atlantis, "Outcast" and "Trio," were the weakest shows of season four so far. But, there’s a simple reason for it. Neither episode featured the whole cast. When the entire group is together, there is excellent cohesion and a spark of urgency. That spark was gone this time around.
This fourth season has been focused on character development. These two episodes were in the same vein. "Outcast" relayed some information about Sheppard’s family; "Trio" tried to make Keller useful to the team outside of her medical training. I really don’t know why McKay was in the show at all. Maybe just comic relief.
"Outcast" begins with Sheppard receiving news of his father’s death. Immediately, he packs up and is in the gate room headed for Earth. At first, he stands there alone; then as he gets ready to head through the gate, Ronon shows up. Sheppard asks him where he’s going and Ronon replies, "With you."
The two of them attend the wake for Sheppard’s father. We’re introduced to Sheppard’s brother, Dave. There is friction between the brothers, which comes as no surprise. Through their terse dialogue we also learn that Sheppard and his father had a falling out – and now that can never be resolved.
The story develops Ronon's character more than Sheppard's. Ronon has been pure warrior, which was needed as a runner from the Wraith. But his human side is starting to show through. For example, his unsolicited accompaniment of Sheppard to Earth denotes a close friendship with and respect for Sheppard. When Sheppard is standing at his father’s casket Ronon is seen just at the edge of view walking over to see his friend but he decides to quietly leave instead. Later on, he shows the same consideration when Sheppard’s ex-wife appears.
A side story in this episode involves a Replicator built by scientists on Earth. Yes, that’s right, the Stargate program has gone to great lengths to eradicate this threat – and it’s still not gone. This Replicator is fairly boring, though. It didn’t want to be shut down so it escaped. It’s "creator" of course doesn’t want it to be killed, so he joins the search. Predictably, he tries to save the beast and gets himself killed by it. This side story also allows us to be re-introduced to Bates, a character from the first season of Atlantis. His fate had been unknown; now we know he’s joined the I.O.A. He helps out in the Replicator search.