For a long time, I didn't realize that in "Time After Time," Omi actually witnessed his friends' deaths. When I realized it, I felt sorry for him. But when I started to develop this idea, it became even more terrifying.
Do you understand how Omi felt when good Chase said he had to drink Lao Mane Long Soup?
He knew he had made a stupid mistake because of his somewhat selfish desire - he had set himself a grand challenge to become a leader (and rid the world of evil), but he hadn't thought his plan through well, so his friends had died. After that, he had no choice but to correct the past, but in the end, it made things worse for the whole world. And now he, who'd made so many senseless sacrifices, watches Chase defect to the Heylin, powerless to oppose his choice. Everything he'd started this for had collapsed completely. And in the end, Chase's sacrifice had done more good than all his sacrifices combined.
(And good Chase doesn't even know how much Omi sacrificed to save him from siding with the Heylin...)
And, frankly, young Chase didn't need this saving (I call him young, not good. Good Chase has no pride, but a sense of responsibility, and he's ashamed that he ever wanted to be evil). He clearly considered himself smart, but was easily deceived (no, he was communicating with a villain, is that a sign of intelligence? Just a thirst to become great), and in general he has a lot of self-importance. But, unlike Guan in the same situation, he betrayed Hannibal and imprisoned him in Ying-Yang World, making things better for everyone. It's ironic, because it was Chase who did more to rid the world of evil by getting rid of... a rival of sorts, an extremely dangerous and cunning one.
Interestingly, both when Omi traveled to the future ruled by Jack Spicer and when he returned to the present, where the Xiaolin Temple had been destroyed, his friends didn't scold him for his mistakes (even the villains, though they didn't know the whole mess started with Omi's disappearance; Chase was actually happy to see him). They helped him fix them. This is great, because Omi himself realized he had made these mistakes and repented.
Unlike Omi, Chase had thought through his plan. He didn't just deceive Omi, but also developed a relationship with him. Hannibal, for example, didn't see Omi as an ally and sought to exploit his weaknesses—his ego and his thirst for knowledge of who he was and who his parents were—which is why Omi distanced himself from his friends, making both himself and them more vulnerable. Chase exploited both Omi's strengths and weaknesses, demonstrating a keen understanding of his own actions and insight. What was he really trying to achieve by making Omi promise not to seek a way to destroy evil and using the "Reversing Mirror"? After all, it's a win-win situation: either Omi destroys good himself, or Chase does it, following his plan (most likely, he also knows a way to destroy good, and his words about the prophecy can confirm this; however, I'm not sure, because he never managed to destroy good after Omi turned evil). But why did he make Omi promise? Wouldn't it have been simpler to let him tell his friends about the way to destroy good? Did he really want to teach him honor? Perhaps the destruction of good begins with the destruction of positive personal qualities, and therefore involves breaking promises and lying? So many questions...
In my opinion, their relationship is the best because it constantly makes me think about their actions and reasons.
I also think it's better to be evil because you were deceived by someone you trusted, than to be evil because you're an idiot and hang out with villains with whom you had no relationship to trust. They were both deceived, but Chase primarily wanted to be important, and Omi wanted to save someone close to him. But hey, if Chase hadn't turned evil, we would have lost such a great villain, so I won't criticize him too much :)