In "Dynamic Duets," it was established that Puck is still doing sex work, or attempting to. He'd been having sex with "cougars" at least since he was sixteen, and saw nothing wrong with that. In a second season episode, I think "The Substitute," Puck said something along the lines of "Mr. Ryerson touched me." I haven't seen any commentary on that. I wasn't watching Glee yet, and I didn't know people were blogging about it. But when people talk about Puck having sex with older women, they don't talk about him being touched by Sandy, and Puck couldn't have been more than sixteen then. Perhaps that contributed at least a bit to his homophobia, though it doesn't seem to have been a necessary factor. But Puck never had any idea that he was damaged by having sex with women more than twice his age. It was accepted as normal or admirable by his male peers.
It still depresses me somewhat that Sam said he lost his virginity when he was working as a stripper, since it seemed like it was the thing to do. There was no "Sam loses his virginity" plotline. Sam losing his virginity that way doesn't seem to have damaged him.
I want some Artie plot. He and Sugar kissed in the wall-painting montage. I don't know where that came from. He wanted to be with her in "Heart," but she decided to date Rory. As I've said a number of times, I am still waiting for an apology from Sugar for saying she had self-diagnosed Asperger's Syndrome, and that was why she was rude. I don't think that's ever going to be picked back up. I don't want Artie with her. I would like for him to get a girlfriend, though. I don't think it would ever happen on the show, but Artie seems heteroflexible enough that it would be possible for him to have an encounter with a guy. That would make for an interesting story. There's plenty of plot Artie could get that wouldn't involve a romance, too.
I would love some development for Tina. At least she got a major part in a competition song, in "Gangnam Style." But there could be plot with her talking. She was shy at first, but she hasn't been shy with the members of New Directions for a long time. It's still all stereotypes with her, when she used to resist the stereotypes. In "Dynamic Duets," she was calling herself "Asian Persuasion." Tina's got a great voice, and doesn't get to sing much. Other New Directions members who don't have such good voices have gotten a lot more songs.
I realized that I had been missing Santana. She was very mean to people, but part of it seemed to be that she was terrified of coming out. She'd seen what had happened to Kurt. She said in "Thanksgiving" that she had Mexican psychic powers. Before that, she had just told Brittany, "I'm Hispanic." Mexico is an interesting choice.
Mike got to sing, and teach dance again. I never identified with him, but he was always decent to Kurt, and stood up for him. At least Mike finally got a plotline in season three, though he wasn't nice to Tina in "Props."
Mercedes could have gotten more development. We never even met her parents, though she does have a choir that shows up. Mercedes had her church community, and knew how to build community. She got more development than some characters. It was interesting to me last time I did a marathon that in the first couple of episodes she used a little African-American Vernacular English here and there, and then it was mostly dropped. As soon as Santana had a few lines, it was established that her first dialect was Standard American English, but Santana would say a sentence or phrase in AAVE every so often. I'm not sure if it was for emphasis or what. Artie used it at times, too, but I've learned that it's appropriation when it's him.
Unique was back in "Thanksgiving." She knew her parents were trying to protect her, but said there would be nothing left to protect if she wasn't allowed to express herself. Unique also said her parents were talking about sending her to a camp for boys who wanted to dress in girls' clothes -- something along those lines. (Edited to add: She said her parents kept talking about sending her to a camp for "little boys who like to wear dresses.") I haven't heard of any camps like that, but I've heard of places that try to "de-gay" people, and it seemed supposed to be like that, a horror. Unique is under serious threat, but is standing up to it. The other members of New Directions don't have any idea of how much danger she's in. I don't think Marley really got it. She was sympathetic, but more focused on her own problems.
I'm still not that interested in Marley. She's supposed to be the new star, but I care much more about some of the other characters. I wasn't too alarmed when she collapsed. An IV of nutrients would help the immediate problem. Marley would obviously be dehydrated and need calories. She needs counseling about eating disorders in the longer term, but I doubt she's going to get that. Marley got a distorted body image very quickly. I wonder if New Directions will be advised to go on with the competition without her. Jake and Unique, and probably Ryder, wouldn't want to. Blaine and Unique could sing, but duets usually mean that the singers are involved, or want to be, or will be. Everyone but Rachel went to the hospital with Quinn when she was in labor. I don't think it's quite like that, but the newer members of ND have bonded with Marley.
(*spoilers and speculation*)
The preview seemed to indicate that Sam and Brittany would kiss. Apparently various members of ND get crushes on each other in a few episodes. I'm sure Unique really wants a boyfriend. She thought Jake was cute, but warned Marley that he was a womanizer. There are really a limited number of crush combinations. Blaine knows that Unique's a girl. Tina and Artie have already dated, as have Artie and Brittany. There's already a Ryder/Marley/Jake love triangle, with Jake having kind of dated Kitty. Marley and Jake have dueted, and so have Marley and Ryder. I'll see what happens in whichever episode it is.