At long last, the prodigal son has returned to Supernatural. The CW show's Jan. 30 episode delivered a heavenly surprise when Jack (Alexander Calvert) finally resurfaced with a renewed purpose. It turns out that Billie (Lisa Berry) brought back the young Nephilim to defeat Chuck (Rob Benedict) once and for all. Nobody was happier to see the sandy-haired half-angel back in his rightful place than Castiel (Misha Collins), who'd been mourning his death all season.

"Cas takes Jack's death very personally. He feels like he fails as a[n] angel. he feels like he failed as a father. He didn't keep his promise," Misha Collins told TV Guide on a recent set visit. "So, ultimately, when [Jack is resurrected], Cas, of everyone, is the most euphoric. He just feels giddy with joy and so happy."

Happiness is a dangerous word to use given the deal Cas made with the Shadow. The angel agreed to return to the Empty for eternity when he reached his highest point of happiness, which he's coming dangerously close to now that Jack's back. With the threat of him being dragged back into that endless void forever looming, let's hope he can keep his feelings in check.

Supernatural Finally Brought Back [Spoiler] and We're Not Okay

And while Cas might be over-the-moon for Jack's return, Sam (Jared Padalecki) and Dean's (Jensen Ackles) feelings about the situation are a little more complicated. Though they've dealt with their fair share of loss over the years, the boys had never experienced the particular kind of grief that comes with losing a child and so, Jack's death affected them differently. Their adoptive son's resurrection is a welcome surprise, but it doesn't exactly erase the pain they've been going through in the past few months. Sam, especially, will be plagued by feelings of guilt and doubt over not just Jack's death, but his delay in letting them know he'd been back.

"We see Sam grieve [but] still hide it because he has work to do. He wants to move forward and be strong, but we see just how much [Sam] missed Jack and felt bad about Jack being gone and then not coming back to Sam and Dean when [he] came back to Earth," Padalecki explained. "[Sam] is kind of wondering, 'Why didn't you come back to us? We had your back, man. I hope you know that we love you,' and struggle with [the] way. Is it because Jack doesn't trust them? Or is it because he's also going through something and he's hiding something? Time will tell."

Supernatural returns with new episodes Monday, March 16 on the CW.

Additional reporting by Lindsay MacDonald

Alex Calvert and Misha Collins, <em>Supernatural</em>Alex Calvert and Misha Collins, Supernatural