I just had a thought: What if Fuuta had such a close bond with Rumerie because they were in the same football team?

I very much believe Fuuta had a particularly close connection with Rumerie, compared to other members of the Dark Triad. He's constantly looking towards Rumerie in Bring It On, and their usernames are seen combined in graffiti in Backdraft.

Now, I never quite understood why there is such an emphasis on Fuuta's passion for football. He talked about football quite a bit in T1, he wears shoes based on football trophies in his birthday art, and Backdraft has multiple allusions to football (the training outfit, the cheering, chanting, stadium corridor). Why so many of these calls to FOOTBALL when it seemingly has no actual relation to the Dark Triad / Twitter cyberbullying?

However, it could make sense if Rumerie was also connected to Fuuta's passion for football! Perhaps they were on the same team, before something or some incident crushed Fuuta's dreams for the sport. Then, they become part of the Dark Triad. For both football and the Dark Triad, they worked together as a team.