Yin and Yang tend to argue and get on each others nerves often, but seeing them work together and get a long is pretty sweet. This is especially happens in "A Toy Story" when Yang earns enough tickets to win a scooter he wanted at a fair; but, after he sees Yin get upset by not being able to get a doll, he gets it for her.
In "Yin Yang Who", although the moment is a bit sad, Yin jumps in front of a Woo Foo Aura Drain attack to protect her brother. She's slowly dying throughout the episode but risked her life just to save him.
Towards the end of "Falling Yin Love", Yang tells Yuck about why Yin is such a great person and deserves a good boyfriend.
Yang: She's smarter than me-which doesn't say much. She's nice and sweet and I know she deserves a nicer first boyfriend than you!
To some extent in the same episode, Yin approaches Yuck smiling and saying she wanted to be close to him; oddly enough, he even smiles at her and leans forward eagerly.
Yin: Oh Yuck, I don't care if it was all a trap. I still wanna be close to you.
Yuck: Y-You do?
For fans of Carl and Herman, there's a blink-and-you'll-miss-it moment in Dojo Alone: when they sneak into the dojo and briefly think Yo is actually home, Herman is visibly scared and jumps into Carl's arms for comfort. Aww, Look! They Really Do Love Each Other!
The entire episode "Dummy Up" is filled with this. When Master Yo leaves, Yang secretly misses him and carries around a ventriloquist doll of Master Yo. Seeing Yang do this is especially touching.