FORGET about Meredith and Derek’s boring on-again, off-again “Grey’s Anatomy” romance.

It’s their colleagues who’ll get the real juicy storylines this season – including a possible lesbian fling between Callie (Sara Ramirez) and Erica (Brooke Smith).

Their relationship seemed destined for a U-turn at the end of last season – when they locked lips in the season finale.

“Callie and Erica have a love story of their own,” “Grey’s” creator Shonda Rhimes tells TV Guide.

“And, yes, it includes Mark.” Who knows what that could mean.

Rhimes had a tough off-season dancing around questions concerning “Grey’s” co-star Katherine Heigl (Izzie), who blasted the show’s writers for not giving her Emmy-quality material. There was some thought that Rhimes might put Izzie in a coma – as a way to shut Heigl’s yap.

If only.

“Izzie’s got a love story – and it’s a big one, one that I’ve been kicking around in my head for a bit . . . one that is so secret that I have not told anyone,” Rhimes says.

Rhimes also says Cristina (Sandra Oh) will experience a new love with “a military guy,” while George (T.R. Knight) and Lexie’s (Chyler Leigh) relationship “is going to take an incredibly unexpected turn.”