Tomoe/Enishi

Wear your cobwebs proudly in your cheap and brittle sight.

Some say Tomoe is an android, that she is emotionless and cold.
If she was emotionless, she would have never fallen into that deep depression after Kiyosato was killed, she would have never gone after Kenshin, she would have never loved Kenshin, she would have never died for him.

My top reason for loving Tomoe is her altruism; she died so Kenshin could have a second chance, because she loved him so much she wanted him to be able to be forgiven, she wanted him to find happiness.

If that's emotionless, then tell me what's love supposed to be then?

Just because she doesn't burst out with every emotion that comes to her mind (like Kaoru, Sanosuke or Yahiko), it doesn't mean she is emotionless.

Tomoe is introverted. Her all-round expression, containing facial and linguistic, or lack thereof, is what she hates about herself. She thinks she killed Kiyosato with it.

Tomoe was happy with Kiyosato, but wasn't able to express her feelings. When Kiyosato went to Kyoto, he wanted to become somebody Tomoe could be proud of calling her husband. Tomoe thinks that if she had been able to tell Kiyosato that it was already enough for her to be happy, he wouldn't have died, because he wouldn't have gone to Kyoto.

Even though she realizes it would be better to find a way to talk her mind, she still doesn't manage to say what she thinks.

When Enishi fights Kenshin, and he is ready to kill him, he sees Tomoe, holding Kenshin, holding back Enishi of what he is about to do.

Enishi realizes his sister wants him to spare Kenshin, wants Kenshin to live.

When Enishi went to the village Tomoe and Kenshin were living in, Tomoe did tell him to leave, to go back to Edo and forget about what had happened. But she did not tell him she had forgiven Kenshin.

And that's the problem: Enishi didn't really know Tomoe wanted him to leave Kenshin alone. Because she never told him right into his face. Of course Enishi saw how Tomoe threw herself in front of Kenshin to save him, but how we know, it is not Enishi's strength to use his eyes properly. Enishi lives in another world. He has hallucinations, and everything he sees he puts together in a way he would like it, or in a way it gives him an excuse for what he is doing. I wouldn't be surprised if Enishi didn't even remember that Tomoe was killed because she tried to save Kenshin, and thought that she had been murdered. This is the Rashomon effect, everybody sees everything in a different light and under other circumstances than anyone else - for Enishi, it wasn't like "My sister threw herself in front of Kenshin because she loved him and wanted him to live, so I mustn't harm him.", it was "My sister threw herself in front of Kenshin and he killed her, so I must take revenge."
An example for this is that Tomoe always smiles in Enishi's mind. Tomoe wasn't a person to laugh much. In the whole story, we actually see her smiling only once. And the way she talks about that Enishi often gives her a hard time with his bratish attitude isn't really a proof of that she often smiled at him. She didn't smile when she was happy - so why should she have smiled when she was stressed?

This shows Enishi's selfishness. Enishi thinks he must kill Kenshin for Tomoe, but in fact, he wants Kenshin suffering because of his own egocentric sake. Enishi and Tomoe are opposites; Tomoe thinks of herself as selfish, although she is not all - Enishi thinks he does this all for Tomoe, and is indeed only selfish. Tomoe thinks about what to express before she does so, and Enishi bursts out without sitting down and rationally thinking about it first. Maybe Tomoe wanted to take revenge on Kenshin in the beginning, but she accepted that Kenshin was a good person. She looked at everything in a very rational way, and she gave Kenshin a second chance. She forgave him. She accepted that images that are burned into one's mind have the power to change.
Enishi claims to do this all because Kenshin took away Tomoe's happiness. But I think the only real reason for Enishi is that he was mad at Kenshin because Tomoe would have preferred to stay with Kenshin. She would have preferred to never come back to Edo, and never pamper Enishi again. But again, Enishi's mind twists this all around until it gives Enishi a more "unchildish" excuse for being mad at Kenshin. It is not Tomoe's happiness Kenshin took away - it's Enishi's.

Enishi stays a child throughout the story. Nothing is rational in his world - Enishi's world is a world created by himself, by his mind. Where Tomoe is forgiving and accepts that she can be wrong, Enishi refuses any of his principles to change. Only at the end he realizes he's been wrong.