Litheran... I disagree with you about Tara. I also used to think she had poor character development, but a friend of mine🙂p) showed me the light!
You see... she starts as this really quiet and shy girl. She stutters all the time, never speaks her mind. Now in Hush, she meets Willow for the first time, and she ends up helping Willow with her(powerful) magic to barricade themselves. The next few episodes shows her getting more comfortable around Willow and magic as a whole, they do spells and she offers a crystal to Will. In 'Goodbye Iowa' her character gets a little bit more complex when we see her purposedly sabotage the spell Willow is trying to do to locate demons. A couple episodes later, Oz comes back and Tara who had slowly started becoming more confident in herself, drops back a step or two when she thinks Willow might just get back with Oz. You can see her start stuttering again in front of him, and pretty much until the end of the episode she seems unconfident that her relationship with Willow will continue(probably because she's afraid that Willow will go with the *normal* girl/boy relationship). To her surprise though, Will picks her and I think it really gave her a huge boost of confidence on the long run. 🙂
In 'Real Me', time has passed and Tara has gotten even more confident. She actually comforts Dawn when she feels left out and explains to Willow how it is to be an *outsider*. For me, in that scene Tara showed maturity and wisdom(which she most likely already had), that we had not really seen before due to her usually quiet and timid approach. 'Family' finally brought us a Tara centered episode. In it, we see her family for the first time and realize(by her attitude and renewed stutter) that they probably had an important part to play in her shy and fragile demeanor. She meets up with her dad at her place and we find out that Tara has some demon in her(which explain why she sabotaged Willow's spell back then), and that it will be revealed on her 20th birthday. Willow comes in after Tara's dad left and for a rare time Tara actually throws a fit about how it isn't always about Will and her friends. At the end of this episode, Buffy and the others stand up for her against her blood family and it's another boost of confidence for her. So much that she stands up against the man who demeaned and belittled her(who also happens to be her dad, mind ya!) and tells him to leave. To me, that is one of the main scene where Tara's character develop.
Later on, in 'The Body', we see Tara comforting somebody again - this time Buffy -, she explains how she felt when her mother died and right there we get some more character development(I'm just sad that we never found out how exactly her mom passed away). In the next episode 'Forever', we again see the wise and confident Tara when she tells both Dawn and Willow that magic can't be used to alter the natural order of things, such as life and death. Would the shy and introverted Tara have spoken so openly if she had not grown by that time? 😉
Another episode where we get some more development for Tara is 'Tough Love'. First, she reveals to Willow that she's concerned about her improved power, and then that she has some fears that Will might not be satisfied dating a woman anymore. This lead to a fight and Willow leaves. Around the middle of the episode, Tara goes to the cultural fair where she is surprised by Glory on a bench. In that scene she shows unbelievable courage when she refuses to reveal the key's identity even though it will lead to her own demise(poor Tara 🙁), yet again expanding on her development.
Next, season six. In her last season on the show, Tara goes on to develop even more. She starts showing even more concerns toward Willow's frivolous use of magic. Thus leading to the scene in 'All The Way' where they argue and Willow rudely imply that she should keep her mouth shut. Tara again shows her improved self-respect by telling Willow off and leaving. In 'OMWF' and 'Tabula Rasa' Tara finds out that her girlfriend used a spell on her, betraying her trust and she only accepts to stay with her because Willow promises that she won't use magic for a week. This sadly doesn't happen and when another Willow's spell ends up wrong, Tara breaks up with her and leave.
Later on in 'Dead Things', we see a new development for Tara. Buffy actually talks to her in private and confide to her about Spike. She looks up about the spell and report to Buffy that she didn't came back wrong, which leads to Buffy crying her heart out and revealing that it has gotten very serious with Spike. Here we see Tara(the used to be shy and unconfident girl) comforting the Slayer. Buffy feels trustful enough of Tara to confide in her what is probably the darkest secret she had at the time... If that isn't development for Tara in regards to the others, I don't know what it is. 😉
We see Tara's compassion and loyalty again when in 'Older And Far Away' she sticks up for Willow's own rights to choose if she will use magic or not. That after Willow abused her and pretty much acted like a crazy overdosed junkie in the previous episodes... God, that makes me love Tara so much. 🙂 Anyway, in her last two episodes(Entropy and Seeing Red), Tara finally gets back with Willow and things seems to be getting better and better until her untimely death, which left us wanting for more.
I personally would have liked to see a darker side to Tara, and maybe that could have been explored in season 7 if she had not been killed. But overall, I think going from that shy girl in 'Hush' to the confident and loveable woman in 'Seeing Red' was quite a character development. I think it's just easy for people(including me the first time around)to not notice her changing through the show, simply because she is not the 'in your face' type. She's in the back, she's often quiet and we are less likely to pay attention to her. But, if we do, there's plenty of development, I tell ya!
So yea... That was pretty much out of topic, but I had to say this! Thanks to my friend for showing me the light about Tara. 😉