Oh man, I've only got fandragons, but these two suit the expression bill easily! And fun fact, they're pretty much nemesis right now. :P
Riptide would be either giving a super smug/arrogant smirk or almost yelling violently (I can post/PM examples from their fights, or you can look up Riptide's run in Championship season 7; Be warned of controversies though).
MadCatter...Honestly, look up the robot. His captain is exactly the face + pose he'd make. :P Alternatively, I feel like the dragon would make the actual face on the robot - creepy eyes and all.
Riptide is very loud and obnoxious. Honestly just known for his arrogance and catchphrase: "LET'S GOOOOOO!". Don't trust his apologies, he may just be trying to look good for others. :P
Ignore his apparel, but his skin (or at least the water parts!) are crucial for his design. He can control water when feeling extreme emotions, and waves are his icon, so he always has some form of wave visible (including as hair).
He does have an alternate design lower down (including anthro dragon), but potential trypophobia warning in advance for anyone who looks; He has circular markings, and while they aren't intended to be eyes, there are multiple ones in certain places so just please stay safe. I also want to get him Multigaze, but I'm too broke to do that right now so don't worry about that right now. xD
MadCatter is rather energetic and prone to showing off for the crowd. He enjoys portraying a contact sport type of persona and enjoys posing for the audience. However, he is also humble and caring when not portraying this persona, and cares a lot for fellow competitors.
However, Cat does have a grudge against Riptide for questionable reasons (okay so this is AU stuff, but even Dragon!MC has a slight disliking toward Riptide, lol) and tends to try avoiding him as often as possible. He still hopes Riptide can mature over time, however, and is trying to let go of the grudge, but it is a difficult process for him.
Ignore his apparel, tbh. I just wanted to try replicating the robot, lol. It didn't quite work out, LOL.
If you want to see the robot design, his profile has the current version. It is kinda dark (not in the way of gore/blood, but it does have a creepy face that could potentially jumpscare people), so be warned about that. I will probably add another (older) version if the robot as well, lol. He can be mechanical if you are okay with giving robot details.
Or I also have Zapper here who's just a loudmouthed, short tempered robot. xD Though also a fandragon.
I otherwise only focus on OCs and none of 'em are dragons. ;3; Though let me know if you'd be open to an OC instead and I can try finding one~ Hard part would be finding one within my priorities since most of them don't have any real facial expressions, LOL (they're mostly robots and shadow creatures).