I had to do it. Homage to Tarantino, nearly verbatim from this scene.
Let’s say that the military isn’t quite up to snuff in terms of containing the outbreak, at least not in terms of Dirk’s standards. He and the other three are confirmed to be infected with the virus (in its beta-form; though not inherently threatening to its host, the more benign version is still thought to evolve into a fully-fledged state of mutation/decay after an unspecified amount of time). Being the loose-cannon soldier he is, Bro’s not going down without a fight.
Though roughly ten years older than their counterparts, Jane/Jake/Roxy/Dirk are still related to John/Rose/Dave/Jade in a parental sort of way. Their exact lineage is unknown to them, and they think themselves siblings and/or cousins. They’re not.