A third storyline could be a sports - related one. They all join a basketball team. Takemichi is the underdog trying to prove himself, Mikey has natural talent but is a bit of a wild card, and Draken is the reliable team captain. They face off against tough opponents, and there are internal team conflicts as well. But in the end, they learn to work together and become a great team.
To write a compelling character interaction, start with understanding their personalities. Takemichi is often determined but a bit clumsy at times. Mikey is strong - willed and has a natural leadership quality, and Draken is the loyal and protective type. So, when writing their interactions, you can show how Takemichi's clumsiness might make Mikey laugh or roll his eyes, while Draken would be there to support Takemichi. For example, if they are in a fight, Takemichi might accidentally trip over his own feet, Mikey would be like 'Seriously, Takemichi?' and Draken would quickly pull Takemichi back to safety.
Mikey might be a character created to tell a story about Pop Rocks. He could be a fictional child used to illustrate the appeal or novelty of these candies. For example, he could be a curious and adventurous little boy who wasn't afraid to try new things, like Pop Rocks, which were quite different from other candies at the time.
As of the current chapters, Draken is still alive. The storylines haven't led to his death. The character has played an important role and continues to be part of the ongoing narrative.