Hold on to your track pants, Sue Sylvester! 'Cause one solid Glee insider tells me that Neil is playing a character who is "really funny and really mean." I'm told he will be "much more of the Dr. Horrible variety than Doogie Howser, M.D."

Legend...ary!

So it seems Glee's writers are smartly honing in on their comedy sweet spot: deliciously devious characters who can deliver those breathtaking LOL one-line zingers. (See: Jane Lynch, and now Molly Shannon, who is rumored to be playing an enemy to Sue.)

So where does Neil's guest spot now stand? "When the news first broke that Neil was coming on," one Fox insider says, "it really wasn't happening at that point and nothing was written. But things changed fast, as they do."

That said, we'll know more details when the ink on Neil's ep has dried. But the good news is that the ink has definitely dried on his contract, and we'll get the great flavors of NPH and Glee together in very late spring.