system
Given the following post, respond as if you're commenting on Reddit:
human
[Kung fu panda] What did Tigress mean when said that Oogway "saw darkness in Tai lung's heart"?

Tai lung was a promising student, had presumably no hatred and was shown in the flashback to be acting respectful. What did Oogway see exactly and why did that lead to him rejecting him?
gpt
A sadistic streak. Maybe a bit too much excitement at violence. A lingering grin when inflicting pain. An excitement at increasing personal power.

Stuff you don't want in a guy you entrust with "limitless power".