Liu Kang and Ryu: Closer Than You Think!
It's already noticeable that fighting games do copy from each other. Now one can see how Liu Kang and Ryu end up having similarities. While Liu Kang is Chinese and Ryu is Japanese, both of them are the heroes of their respective series. Liu Kang ended up having similarities with Ryu as Mortal Kombat progressed.
Liu Kang in Mortal Kombat II had some similarities with Ryu. Kung Lao was made his best friend and friendly rival at the same time, notice Liu Kang in Mortal Kombat II has a red gi like Ryu does. I guess they were inspired by Street Fighter II to create Kung Lao as a Ken-type character and giving Liu Kang his gi was part of it.
After Mortal Kombat I, Liu Kang and Shang Tsung ended up having a Ryu vs. Akuma/Gouki type of rivalry. Shang Tsung plays the dark malevolent force, equivalent to that of Akuma who was a hidden boss in Super Street Fighter II Turbo. It was more or less a dishonorable rivalry. After that, Liu Kang would also beat the main antagonist for most games, Shao Kahn.
Liu Kang also has an evil side to fight. If Ryu had his Evil Ryu alter ego, Mortal Kombat Deception introduced the concept of Evil Liu Kang, a name I dubbed for the corpse form of Liu Kang had. In Mortal Kombat X, not-so-surprising is how Liu Kang returns as a revenant to a character he supposedly defeated in his past life in Mortal Kombat 4/Gold. In Mortal Kombat X, Liu Kang has a Dualist variation that allows him to switch between darkness and light.