Like I've said before, I think of Yugi and Joey as being two of the only people in the entire series who understand Kaiba on any level.
Also, I think it's cute that Yugi apologizes for "yelling" at Tristan when most of us would have called it "stern telling off that Tristan needed."
I don't have that much to say about page 20 except that for some reason, adding lines around Serenity made the first panel much more dynamic, and that I like the effect that adding a gradient over the entire page had on the feel of the page.
I love page 21. I think it's the best page in this sequence, because of how well it shows the dynamics between the two characters (and because of how pokeable Yugi is in the first panel.)
Poke him! Poke him I say!
Also, this is the second time I've made a joke about drugs in this fancomic. There must be something wrong with me.
Of course, page 22 is good for interaction too, and I like it in part because it lets Joey's more vulnerable side out (a side of him I don't go into very often).
"Were you aware my sister has a crush on Kaiba?" is Joey's way of changing the subject to Kaiba without seeming like he actually gives a care about Kaiba (even though he does-- as I noted before he pretends to be unconscious whilst Kaiba is apologizing for Kaiba's benefit).
XD Joey thinks Kaiba is funny. Clueless, and funny.
Yugi: "I am the rock!"
(is smacked)