Dean was exceptionally ruthless during the midseason finale of "Supernatural" season 10 as he gave in to the never-ending struggle with the Mark of Cain, and it seems like the dark version of Dean will stay for a little longer. 

In the upcoming episodes of The CW's long-running horror fantasy drama, Dean (Jensen Ackles) will be hunting Metatron (Curtis Armstrong) to avenge his transformation as a demon. In the promo, Dean goes all-out to hurt the angel, even hurting those who try to stop him. The midseason premiere episode of the series titled "The Hunter Games" shows Metatron chained and bound in a chair after Dean captures him.  

In the promo, Metatron describes his captor as, "Full-out, foaming-at-the-mouth maniac. He's gone nuclear." 

The teaser also shows Dean's younger brother Sam (Jared Padalecki) and their friend Castiel (Misha Collins) trying to stop him from his murderous plans. Can they help him go back to his old, saner self? 

Meanwhile, a slew of former characters will reportedly come back in the remaining episodes of the series. One of them, naturally, is Cain (Timothy Omundson). He is the reason why Dean is acting the way he is now, and fans will surely enjoy seeing him back in the series to find out how his reappearance could affect Demon Dean. 

Omundson himself confirmed his return on The CW series on his Twitter account, saying: 

Why am I going to Vancouver? 

A) PSYCH reunion 

B) Bringing Cain back to #SUPERNATURAL 

C) Extradition 

Hint: Not A or C" 

The other returning character in the show is Charlie (Felicia Day). She is expected to return from Oz, probably to help the brothers just like what she always did in her past appearances in the show. 

Both Cain and Charlie will return in the later episodes of "Supernatural" season 10, due to return on Jan. 20, 2015 after its winter hiatus.