Barry (Grant Gustin) and the team at S.T.A.R. Labs spend a lot of time on "The Flash" focusing on the future — traveling further into it, changing it, saving it. In episode 11 of the CW series second season, "Reverse Flash Returns," it would take facing a foe from the future to tie up some loose ends from Barry's past. 

Not surprisingly, given the episode's on-the-nose title, Eobard Thawne (Matt Letscher), aka Reverse Flash, is back in Central City. "How," fans might ask. Well, as Dr. Wells (Tom Cavanagh) explains, although Eddie (Rick Cosnett) sacrificed himself in the Season 1 finale and erased Thawne from existence, the villain's timeline now begins in the future. This version of Thawne is the one before he went back in time to be erased in the first place!

Right now, Thawne is scouting for The Flash, trying to identify the time period in which Barry lives — bingo! However, it will not be until Thawne learns Barry's name that he goes back in time and kills the superhero's mother. In the meantime, Reverse Flash uses a staged runaway oil tanker to bait The Flash into showing himself, then, having obtained the information he came for, kidnaps Dr. McGee (Amanda Pays) at Mercury Labs and forced her to build a Tachyon particle-fueled time sphere to get him home.

Luckily, Cisco (Carlos Valdes) gets a vibe of Thawne's attack with the help of a special pair of goggles fashioned by Wells, who figured out that adrenaline triggers Cisco's vision. However, this vibe is special. Cisco witnesses Thawne killing Dr. McGee ... but in the future! Yes, Cisco can see the future. Now Barry, who is more than a bit shaken up to see his worst enemy back in action, has three hours to find his old (new?) rival and stop him from returning home.

Watch Barry confront Reverse Flash in the scene below:

Meanwhile, Barry is the not the only one confronting a past wound. Joe (Jesse Martin) reveals that Francine (Vanessa Williams) is not doing well and that it would be a good idea for Iris (Candice Patton) to pay her mother a visit and say her goodbyes. She goes and, though it is hard for her, she forgives her mother for leaving when she was a child. Afterwards, she is surprised how emotional she is despite barely even knowing Francine. 

Joe and Iris also urge Wally (Keiynan Lonsdale) to visit Francine, but he is still angry that she only just told him about his father and sister. However, after a very moving speech, in which Iris opens up to Wally about losing Eddie, he changes his mind. He only has one condition — he want Iris to come with him.  

Back at the S.T.A.R. Labs, Cisco and Caitlin (Danielle Panabaker) keep an eye out around the city for Tachyon readings. Eventually, they get a hit and Barry races off and stops Thawne just before he kills Dr. McGee. The Flash gives Thawne a pretty savage beating  — clearly, he still has a grudge — but eventually he brings the baddie back to S.T.A.R. Labs where he is locked in a vault. 

Unfortunately, messing with the timeline has consequences. In this case, Cisco starts seizing and disappearing from existence the same way Thawne did in Season 1. Wells concludes that the only way they can save him is to send Thawne home and let the timeline play out organically — i.e. let him kill his mother, hijack Earth 1 Wells' body, etc. After some initial reluctance, Barry realizes it is the only way to save Cisco and he does not want to lose anyone else to Thawne. Barry and Reverse Flash team up to create enough speed in the particle accelerator to power Thawne through the time sphere back to the future. 

Thawne promises to return for The Flash.

"I'll be ready," Barry assures him, "every time."

Now Barry has one more problem to deal with — Patty (Shantel VanSanten). He has mostly been giving his ex the silent treatment since their breakup in episode 10, saying he does not want to stand in her way of fulfilling her dream to become a CSI. However, Patty wants some closure. She does some digging and after reviewing some case files, she realizes only one thing could explain how Barry had solved many of his cases — he is The Flash.

First, Patty confronts Joe, who does his best to preserve Barry's secret, but she tells him he is terrible liar. Then, she goes to Barry, even promising to stay in Central City if he just tells her the truth. However, Barry does not want to make Patty a target for Zoom (Tony Todd) by revealing his identity. He lies stone faced to a teary eyed Patty. 

Patty, though, has one more trick up her sleeve before leaving the show. In the episode's last scene, she calls Barry and says her train is being held up by a man with a gun. Barry, as The Flash, races to the scene, but when he gets there, there is no gunman, just Patty. In the middle of the crowded train car, a costumed-Barry and Patty exchange a knowing look. 

"I just wanted to make sure everything was OK," says The Flash with a smile, before speeding off. 

"Goodbye, Barry," whispers Patty.

"The Flash" airs Tuesdays at 8 p.m. EST on the CW.