We don't know the entire context but the Visitor's death at the hands of Rodimus in the first issue. A Cybertronian being killed by another member of their dying species, and probably the first time the Visitor came across another Cybertronian in a long while.
Issue 3 reveals the heartbreaking way Rodimus lost his two companions Gripper and Strongarm. Gripper had an accident and lacking the knowledge to repair him Rodimus and Strongarm were forced to watch him die. Strongarm meanwhile crossed the Despair Event Horizon and tried to take off in their ship to find other Cybertronians. Rodimus tried to stop her but accidentally killed her...
