While Demetri wouldn’t be a fast-learner and had to learn to get over his fears, he becomes a solid combatant in Season 3 and gains more confidence (and a girlfriend) in the process.
Demetri has had one of the most entertaining arcs on Cobra Kai.
This would lead him to join Miyagi-Do in Season 2 and learn karate from Daniel LaRusso.
He began as the nerdy friend of Miguel Diaz and Eli Moskowitz but, when his two classmates join up with Cobra Kai and adopt new attitudes, Demetri is thrown for a loop.