Popular guest star Jeffrey Dean Morgan is on his way back to Grey's Anatomy. That much has been confirmed - but when, why, and how?

Is Grey's Anatomy really going to kill Izzie, as has been rumored frequently, with Denny resurfacing to welcome her to the afterlife? Not likely.

For starters, at least one inside source says there are no plans to off Izzie as a means of punishing outspoken cast member Katherine Heigl.

Second, Morgan already filmed his scenes, which are to air in the season premiere, so the timing is wrong for this stunning development.

But ABC Entertainment chief Steve McPherson issued vague denials of a plan to eliminate Izzie, and another insider says that the rumored brain tumor contracted by Dr. Stevens was indeed the plan for Heigl's character in Season Five.

After her diagnosis, Izzie was to see “visions” of Denny.

Of course, if that was (or is) the plan, Shonda Rhimes may change it since the word is out. She’s not a fan of Grey's Anatomy spoilers (with the exception of her giving away the Mer-Der reunion at the end of Season 4 weeks beforehand).

A few seasons back, E! Online reported that Cristina Yang was to have a lesbian storyline. That plan? Scrapped, then revamped (much) later in the form of Callica.

The conclusion is that we're stumped. Morgan's casting confirmation lends credence to the notion that the brain tumor plot could still happen, but the reports we're hearing the subject are conflicting and far from set in stone.

What do you think of Jeffrey Dean Morgan returning to Grey’s Anatomy - and is the brain tumor a good idea? Tell us what you think - and hope.

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.