"The Flash" and "Arrow" both side-tracked from their respective storylines to take time for backdoor episodes "Legends of Today" and "Legends of Yesterday", which heralded the upcoming The CW series "Legends of Tomorrow" ahead of its January premiere. However, it is time to get back on track, and in the upcoming Season 2 Episode 9 of "The Flash", we will see Barry (Grant Gustin) facing off against some of the greatest villains simultaneously.

In the promo for "Running to Stand Still", we see the return of Trickster aka James Jesse (Mark Hamill) and Weather Wizard aka Mark Mardon (Liam McIntyre) to Central City, and they are both there predominantly to kill the Flash. They have sought the support Captain Cold (Wentworth Miller), the one villain who is as close to Barry as a villain can get.

The last we saw Cold, he was shown as sort of an anti-hero who loves his sister unconditionally. Barry even helped him out, and it seemed like they shared camaraderie. Moreover, we know he is not just going to be a hero, but a "legend" soon, so it is impossible to believe he would actually go through with the other villains' plans to kill Barry; in fact he would be most probably seen redeeming himself.

Also Read: Here is why Barry's father Henry Allen is Zoom 

The Weather Wizard, however, is aware of Barry's fight with Zoom, and how he was almost killed. They therefore know the Flash is vulnerable, so it would easy for them to plan an attack. Moreover, it is the holiday season, and the speedster was hoping for a joyous celebration with Patty (Shantel VanSanten).

However, there is more for Barry to worry about this Christmas, because along with the threat of the villains, Barry will also have to deal with the huge news Iris (Candice Patton) drops on him. Although it is not clear what the piece of information is, we assume it is going to be about her younger brother.

As fans know, Iris' mother (Vanessa A Williams), who had arrived in Central City, revealed to Iris she has a younger brother, Wally West (Keiynan Lonsdale). This revelation during Christmas celebration would provide the right segue for "The Flash" to introduce Wally aka Kid Flash in the show.

Watch Season 2 Episode 9 of "The Flash" at 8 pm (EST) on Tuesday, 8 December. You can also live-stream "Running to Stand Still" via CWTV.