In episode 8 of "The Flash" the Starling City crew from "Arrow" stopped by for the big crossover event, but Oliver Queen (Stephen Amell) makes no such appearance in the Season 2 winter finale, "Running to Stand Still." Instead, Barry had his hands full with plenty of returning characters from the show's own universe, including . Plus, as Zoom (Tony Todd) reminds everyone in the episode's cold open with Wells (Tom Cavanagh) -- it is Christmas! 

Not only is it Christmas on "The Flash," but it is a White Christmas. Snow is falling in Central City even though the forecast was predicting clear weather. Unfortunately, the weather surprise is not a Christmas miracle, but the work of Mark Mardon aka the Weather Wizard (Liam McIntyre). Mardon pulls the blizzard stunt to break Leonard Snart (Wentworth Miller) and James Jesse, aka the Trickster (guest star Mark Hamill), out of Iron Heights to kill the Flash. Jesse is on board, of course, but Snart turns down the gig. 

Barry (Grant Gustin) and Iris (Candice Patton) walk into Barry's house to find Snart waiting for them with a sinister cup of hot chocolate -- Barry is, sadly, out of tiny marshmallows. He warns Barry that Mardon and the Trickster are after him. He says he did not join because there was no money in it, but Barry calls him on owing Barry for saving Snart's sister. He wants Snart to help him stop the other two, but the now-free Captain Cold is not interested.

When Barry and Iris were interrupted by Snart, Iris had just confessed that she had found out Joe had another son, Wally West (Keiynan Lonsdale), with Francine (Vanessa Williams). Francine never told Joe (Jesse L. Martin) she was pregnant when she left. Iris and Barry agree to tell him together. When they corner Joe at the police station, Iris breaks the news. Joe is floored and it should be noted that Jesse L. Martin kills it in this scene -- the tremble in his voice when he finds out Wally's name surely made tons of "Flash" fans well up. The detective fears lying about Francine being dead all these years was not really to protect Iris, but to shield himself from Francinse, a decision he feels cost him knowing his son. 

Meanwhile, Mardon and the Trickster are up to no good. Jesse poses as a mall Santa and gives out wrapped bombs to hundreds of unsuspecting kids and Mardon, who can now fly, lures Barry to the scene. They give Barry a tough choice, let them kill him or let all the kids be killed. Barry lets Mardon take him down and Barry takes quite a beating as Wells and Cisco (Carlos Valdes) devise a (rather farfetched) plan to use magnetism to use one of the bombs to pull al the others into a portal created by the portal gun. It works, of course, and sets Cisco up for a pretty sweet "Good Will Hunting"/"Breaking Bad" shout out:

"How do you like them magnets, b----?"

 When Barry hears he is in the clear he makes quick work of the two villains, but when Patty (Shantel VanSanten) shows up to make the arrest, she pulls her gun on Mardon instead -- remember, Mardon killed her father in a bank robbery.

All episode, since Patty found out Mardon was free again, Barry (as Barry) has not been able to get his rattled girlfriend to talk to him. As the Flash on the other hand, he saved her when she went rogue to track down Mardon and the Trickster at their hideout. Afterwards, Patty confesses that she skipped out on working in her Dad's store the day he was killed. She believed it is her fault he died because she should have been the one delivering the deposits to the bank. 

All of this leads to Patty considering taking justince into her own hands when she has Mardon at gunpoint after the whole bombing-kids fiasco. Barry (as the Flash) pleads with her not to do it. He knows all too well that revenge does not heal any wounds. He warns she will distance herself from everyone she cares about if she pulls the trigger and, eventually, Patty reaches for her handcuffs instead. 

Afterwards, Barry learns from Patty's noble move and decides to try and forgive Wells -- Earth 1 Wells. Plus, Joe stops by to admit he is now ready and excited to meet his new son. However, he does give Barry his watch, the gift always meant to give "to his son" -- Aw!

As if that was not enough emotion to go around, Jay (Teddy Sears) and Caitlin (Danielle Panabaker) share an overdue kiss on Christmas eve at Joe and Barry's house and then, an unexpected visitor shows up -- Wally West! At first, he offers to come back at another time, but a shell shocked Joe and Iris invite him into the house.

Read all about Wally's arrival to "The Flash" in Keiynan Lonsdale's interview with International Business Times HERE

In the episode's last scene, fans find out why Wells has been so stressed since his cold open encounter with Zoom. The big bad guy is making Wells an offer he cannot refuse -- help him steal the Flash's speed and he will let Jesse (Violett Beane), his daughter, live. 

"I'll do it," Wells promises. 

"The Flash" will return in early 2016.