Because not every change Five and his siblings make to the past affects them in the future, they were fairly lax about living their lives in the ’60s. Since none of the superpowered kids would be born until the ’80s, it seemed like they were safe to do as they pleased after Five accidentally scattered them across the decade at the end of season 1.
However, since then, Five and his family have learned the hard way that the Butterfly Effect is real. While it’s true that traveling back in time won’t automatically mess with the characters’ timelines that doesn’t mean they’re immune from unexpected consequences. Case in point: When they return to the present day at the end of season 2, they find an entirely different group of people at The Umbrella Academy, which is now known as The Sparrow Academy.
It’s unclear how this massive shift in their own timelines will play out in season 3, but it seems safe to assume Five will have a greater respect for the Butterfly Effect moving forward.
Time travel is always complicated, but for Five, the concept is even trickier than usual, because even when he tries to follow his own rules, he just can’t seem to escape the unforeseen consequences of his trips.