The Couple

The first real contact between Shannon and Sayid was in episode 12, where Sayid asked Shannon to help him with the maps he found.
She agreed to that, but Sayid got a little angry, when Shannon could not translate the French very well.
At the end of the 12th episode Shannon told Sayid, that Danielle wrote a French song on the maps and because Sayid asked her about the song, Shannon sang it for him.

Until episode 15 nothing interesting happened, but then Shannon doctored Sayid. He had a wound from the fight with Ethan.

Episode 17 was a great episode for all Shannon and Sayid fans, because Shannon kissed Sayid at the end of the episode!
The first real action between them. Before this kiss, Shannon and Sayid talked. Sayid then talked to Boone, because he wanted to tell him that there might be more between him and Shannon than just being friends.
Boone then told Sayid, that Shannon likes older man, because they can help her. When Sayid talked to Shannon again, she knew that Boone told Sayid something about her.

Because Sayid went with Charlie and Jack in episode 18 to find Hurley, Shannon was really worried about Sayid and he bid her goodbye.
He came back and everything was good. ;)