As the series progresses, what will prevent Sara Lance from finally taking her revenge on Damien Darhk, the man who killed her sister?

As it turns out, it's the same thing that kept Rip Hunter from giving her the go-ahead: an understanding of the consequences.

“The thing is, I can’t kill him. If I kill him in 1942 or 1952, all of those years that he was supposed to do everything would be messed up; it’s a big change to history. So I wouldn’t be able to even kill him,” actress Caity Lotz, who plays Sara on DC's Legends of Tomorrow, told ComicBook.com during a visit to the show's set. “I think she’s struggling, now that she’s captain, with this higher sense of purpose. It’s not just all about her; she has to consider other people. You see what happens with Barry Allen when he changed the timeline. She’s coming around and being like ‘I have to accept this,’ but I still think there’s something in her that is always going to want to change it and I don’t know, if she had the opportunity, if she would pass it up. I think it’s still a big area of conflict for her. And of course she misses her sister.”

That journey is as interesting for Lotz as it is for fans: she said during the interview that she hadn't really noticed the incremental progress until the series started airing on TV and she went back to the start of the season to watch her character change.

“I think it’s a lot of responsibility for her. I was actually watching Episode 1 and was like, ‘Oh yeah, she does change.’ She didn’t care and was more childish and now she’s in this position of more responsibility and I think it is changing her a bit,” Lotz said. “Her sister did everything to bring her back to life, she risked everything to bring her back, and how could she not do the same for her? I think the difference here is that when Laurel brought Sara back, she wasn’t thinking about affecting the timeline or the world. Sara, if she changes something like that, is more aware of the infinite ripple effect that could have and how many other people’s lives could be messed up.”

DC's Legends of Tomorrow airs on Thursday nights at 8 p.m. ET/PT on The CW.