It's so easy to keep the superficial part of Eriol in your mind. Or even better: to keep the superficial part of anime!Eriol -who's still pretty cool and funny, but lacks a lot of the depth manga!Eriol contains. Also, the fact a big portion of this fandom's fanfiction writers love to do AUs and change the characters' traits for their, um, stories' sake gets to confuse a lot of fans. So, this section will try to debunk some urban myths that aren't canon-compatible.

Número uno: CCS doesn't have real villains. Sure, we've had several antagonists, but antagonism ≠ villainy to me. If that's the case, we should toss in Yue and some of the cards to the non-existent villain list. And yet, I haven't seen the fandom accusing them. For me, villains are immoral characters who go against the protagonists. You can be an antagonist while being a nice guy, as long as your goals clash with the main characters' or your actions are opposing theirs.

(Note: The thesaurus I checked doesn't list villain as a synonym for antagonist.)

Número dos: Eriol is not evil. Might be occasionally creepy, but not evil. If after his explanations at the end of the series you still believe he's the devil incarnated (pun not intended), then you need to pay more attention to the plot.

His mission is not entirely selfish; while it's not exactly a bed of roses, he doesn't particularly enjoy other people's suffering. He honestly wants to help, believe it or not. Alright, his ways are unconventional, he's amused by the way persons around him think and behave, he gives unwanted advices just because he feels like it and he's always smiling in creepy satisfaction, but that's because he knows they're going to work it out beforehand and nobody will get really hurt.

Let's take the final battle, which is more or less the same in both media. He casts the biggest spell, and hides the sun and the moon, causing the entire city -well, not the entire thing, but almost- to sleep. He looks rather cruel in that episode/chapter, but he has a point. If he didn't pressure Sakura and went easy on her, she wouldn't be able to recover from the shock. So he and his guardians attacked them, so Sakura is unable to doubt he's for real. However, I believe he told a white lie: I personally doubt he'd let the whole city to sleep forever. Because he predicted Sakura could break the spell within the deadline. In the manga, he'd sometimes let a gentle smile or two out when he pushes Sakura to the answer. If he really was evil, he wouldn't feel that way over the fact Sakura is pwning him.

More hints he's not teh evil:

In episode 63 (Sakura, the Pool, and the Big Wave) he's concerned he could've make Rika Sasaki scared of swimming because his spell almost drowned her.

In episode 64 (Sakura and the Ski School Blizzard) he stops the avalanche before it buries the ski lodge, and admits: "The thing I fear is causing [Sakura] pain... But I guess I can't help that, can I?"

In volume 8, he causes a fog during Sakura's cold. Then he feels genuinely sad and sorry when he realizes she had a fever, since he didn't know she was sick. Then he heals her, with a sweet expression in his face, and leaves her with his coat over her body.

Those are my arguments, from both canons, that show Eriol actually cares.

And there's the real motif he went to Tomoeda in the first place. As the holder of Clow's memories, he knew the cards would be useless with the time. Their powers needed to match their new Mistress'. The only one who could save and change them was Sakura. However, changing them just like that could be dangerous. That's why Eriol provoked everything: that way, the cards would change slowly and she could get progressively stronger.

He had good and noble intentions beneath the façade, as you see; he truly wanted to help. And Sakura was thankful and forgave him. She understood Eriol cares about her as an indirect father, and as Clow's reincarnation he wanted to see the guardians and cards happy with their new life. Hell, he even helps Li and pushes the Syaoran/Sakura in indirect ways. If the characters forgave Eriol's methods, why can't you?

Ah, anime-only fans...

This is something that was cut off the TV series. The answer is in the manga. Moreover, in volume 11.

And later on, after the last battle...

So basically, Eriol never was an eleven/twelve-year-old. He was "born" with a child's body when Clow died, as we can see in Sakura's vision on volume 10. It's just that he didn't allow himself to grow up until the card change happened. He thought it was more convenient if he was Sakura's age when that happened, so he could get close without getting suspicions -Kaho's method of becoming a substitute teacher comes to mind, but that limited her role in Sakura's daily life a lot. Both things -not growing up, and becoming a classmate- are not that new in CLAMPverse. Yue, after all, had Yukito who's Touya's classmate as an alter ego. And there are mangas like Magic Knight Rayearth in which some characters stayed in children's bodies for years -namely, Clef and Emerauld.

If Eriol had chosen to grow up normally, there are strong chances he'd be as old as Sakura's father. And Fujitaka is in his forties. Yup, he's pretty much, mentally, an adult; and I haven't even added the hundreds of years of Clow's memories -nope, not an overstatement: they are centuries. Just so you know~

Eh. No. No, he does not.

Most of the rabid Eriol/Tomoyo shippers tend to only look at fanon and anime canon. Apparently, anime!Eriol seems not interested in or explicitly dating anyone. The Eriol/Kaho hints were diluted by animators, perhaps because they didn't go with the Eriol-is-an-adult-really fact, and Madhouse didn't seem to be comfortable with all the age gap relationships (ain't that right, Terada?) But how did it go from "we're not telling if Eriol and Kaho are or not an item" to "ZOMG Eriol is secretly in wub with Tomoyo and he stayed/will return to Tomoeda to win her heart!"? Because I've watched the anime three times, and I still don't see any Eriol/Tomoyo hint. At all.

In the manga canon, it's even more farfetched to look for hints. The only times Eriol and Tomoyo talk to each other is to discuss Sakura, or Kaho, or the way Eriol looks at Sakura, or the way Eriol looks at Kaho. Complimenting someone for their perspicacity and observation skills is not love. Saying someone could be kind is not love. Wanting to be someone's penpal is not love. Especially if pages later one of them is accepting a third person's love confession and grabs her hand.

Eriol likes Kaho Mizuki a lot. Tomoyo knows Eriol likes Kaho Mizuki a lot. Tomoyo is amused because Eriol liked Kaho Mizuki a lot. This is canon. It's all over volume 12.

And before people call (again) Kaho a pedophile or a shoutacon because she loves Eriol, I'll point at #2. He's mentally an adult. She fell in love with an adult man who happened to be stuck as jailbait. But don't CLAMP tend to say looks can deceive and love is blind? I think that it's Eriol who's the cradle-robber and not the other way around, but that's just me.

I see nothing wrong with shipping Eriol/Tomoyo. Ship what you want, people! Personally, I liked how anime!Eriol would look good with Naoko or even Yamazaki, although now I ship manga!Eriol/Kaho. But fans? Stop saying it's canon: your pairing is fanon and non-official. CLAMP ship Eriol/Kaho, period. And please stop bashing Kaho without thinking over a little. She's a really sweet person in the manga, and she truly loves Eriol, so don't misjudge her so fast.