Finally, Barry Allen (Grant Gustin) can sleep soundly -- knowing at least one major timeline change isn't his fault. In the first part of the "Invasion!" crossover, it's revealed that Professor Stein (Victor Garber) now has a daughter. But how did she get there?

The key comes from the episode description for the "Legends of Tomorrow" segment of the crossover. "[Stein] is distracted by the aberration he realizes he created in 1987."

RELATED: 10 ‘Invasion!’ teases for the ‘Arrow’-verse crossover

While the "Invasion!" episode of "The Flash" led to many being disgruntled with Barry for the events of Flashpoint -- Diggle (David Ramsey) has a legitimate gripe with the speedster, for erasing his daughter -- Stein is the only one to blame for the changes in his life.

Honestly, that should go a long way in showing that while Barry may have acted selfishly in creating Flashpoint, he's not the only one that has misused time. Sometimes people simply can't help themselves when it comes to major moments in their own life.

RELATED: The moment The CW became a superhero juggernaut

We've had a lot of fun painting Barry as "The Flash's" biggest villain because of the terrible things that happen when he goes back in time. Sometimes it just can't be helped, though. At the end of the day these people are humans -- sans Kara (Melissa Benoist), of course -- and humans are flawed.

But what happens from here? This change in Stein's life is a major one and given his science-driven mind, it's not likely to be something he just lets go. Will he want to fix the "aberration"? Can he bond with his daughter? And if the aberration "distracts" him from the task at hand, defeating the Dominators, how can he focus on the greater good long enough for the assembled superteam to save the day?

RELATED: ‘The Flash’: What makes Killer Frost scary is she’s right about Barry

Let the "Invasion!" crossover continue... On "Arrow's" 100th episode Wednesday, Nov. 30 at 8 p.m. ET/PT on the CW.

Posted by:Chris E. Hayner

Chris E. Hayner is equal parts nerd, crazy person and coffee. He watches too much TV, knows more about pro wrestling than you do and remembers every single show from the TGIF lineup. You may have seen him as a pro-shark protester in "Sharknado 3." His eventual memoir will be called "You're Wrong, Here's Why..." TV words to live by: "I'm a firm believer that sometimes it's right to do the wrong thing."