Eriol has two companions who counterpart the two primary magical associates of Sakura. Spinel Sun, aka Supi, is Kero's counter, and Ruby Moon is Yue's. I absolutely adore these characters, so more likely than not I'll have more than one sentence worth of commentary about them eventually (hard to decide to what to say in these precarious spoiler terrain situations).
This section should be off to a pathetically slow start, but maybe it'll expand before too terribly many years (hopefully that was an exaggeration!) have passed.
Episode #: 50: Sakura, Syaoran, and the Invisible Threads
Stats: 3 layers, some are stuck, A2 KEY/B2/C1 KEY
Size: 18.25" tall x 10.5" wide
Sketches: 1 matching (A2, burgundy only), unstuck
Comments: Eriol in Clow garb! Looking part creepy, part kind, and part enjoying the opium life... which is pretty much how he is. Maybe not the latter part, but I haven't seen any proof that it isn't the case. This is such a beautiful pan cel! Unfortunately the rich shaded burgundy backing turned out completely wrong in the scan. Um... look at that part from a distance. ;) Maybe I'll attempt a rescan at some point. This is right after he'd been controlling Li with thread, he is finally shown without shading as he comments to Sakura-chan (she isn't there, but she had asked the question earlier) that this is another thing people can do with thread. His puppeteer hand is still up here, as the threads disappear.
Episode #: 47: Sakura and the Mysterious Transfer Student
Stats: 1 layer, A5 KEY
Size: 12.5" wide x 10.5 tall
Sketches: 1 matching, unstuck
Comments: Eriol again. This is his first appearance (barring the quick bits of him and his pet-friends earlier in the episode) as the new transfer student in the class. Sakura is watching him, thinking he looks kind, as he stands at the front of the class waiting for Terada-sensei to introduce him.