'Supernatural' season 12 episode 15 spoilers, news: Winchester family divided; Lucifer gets closer to finding his unborn child

The Winchesters is a family that is divided because of the British Men of Letters. Meanwhile, it seems that Lucifer (Mark Pellegrino) will soon be able to locate his unborn child.
Previously on "Supernatural" season 12, Mary (Samantha Smith) tried to convince his two boys in joining the British Men of Letters so that, someday, they could finally live a life that doesn't involve hunting demons or saving the world from evil destruction.
Sam (Jared Padalecki), after killing the alpha vampire, finally gave in to Mary's plea. However, Dean (Jensen Ackles) still refused to join his mother and brother in uniting with the British Men of Letters.
There is no telling how long Dean will resist joining the British Men of Letters, but it is also possible that the British Men of Letters will do something unacceptable to Sam and Mary. Not only will this prove Dean right about not trusting the British Men of Letters, it can also lead to the Winchesters fighting the said organization off as one happy and united family.
Meanwhile, on the next episode of "Supernatural" season 12, which is titled "Somewhere Between Heaven and Hell," it appears that Lucifer is going to be step closer to finding his baby boy.
"An attack by an invisible hellhound at a campsite leads Sam and Dean to investigate the mysterious circumstances. Meanwhile, two of Crowley's (Mark A. Sheppard) own personal demons uncover what he has been hiding. Castiel (Misha Collins) gets a lead on Kelly Kline (Courtney Ford)," the episode's listing on The Futon Critic reads.
Although it will be Castiel who finds a lead towards finding Kelly, the episode 15 promo reveals that the hellhound Sam and Dean will be investigating is actually Lucifer's.
"Supernatural" season 12 episode 15 is scheduled to air on Thursday, March 9, at 8 p.m. ET on The CW.