‘Vampire Diaries’ Season 4 Spoilers: More Information on Tyler's Old Acquaintance Hayley, Plus Dr. Fell’s Post-Alaric Role [VIDEO]

While the key plot line this season will be Elena's transition into a vampire, that doesn't mean the other members of the Mystic Falls supernatural gang will be just sitting around. Tyler for instance, will be dealing with some issues of his own.

Fans of the series will remember that when season four picks up, Tyler won't actually be Tyler. In the season three finale, viewers watched as Bonnie surprisingly put Klaus (whose eternal life was in jeopardy due to crazy vampire killing Alaric) in Tyler's body. Besides dealing with the original vampire macking on his girlfriend Caroline while using his body, Tyler will also have to deal with a string of newcomers on the show.

Those newcomers include two new hybrid vampires who are devoted to Klaus, and Hayley, an old connection of Tyler's. So who exactly is Hayley, and does Caroline need to worry? Hayley's role on "The Vampire Diaries" has been kept very hush hush, but luckily for us "Secret Circle" star Phoebe Tonkin is ready to open up about her new character.

"I like that she's a world traveler, a bit tomboy, pretty ballsy, and provocative, but not the way Faye was on 'Secret Circle,'" Tonkin said to WetPaint.com of her role. "Hayley just doesn't have a filter. She didn't really have parental figures in her life, and I like that kind of a person. I like that she's tough and tries to keep up with the boys."

Fans will have to wait until the series starts up again to find out if Hayley "tries to keep up with the boys" as a human or wolf...or possibly even a hybrid.

As for another Mystic Falls resident dealing with the crazy Alaric aftermath, Dr. Meredith Fell has no plans on going anywhere after her latest relationship was buried.

Last season, crazy vampire Alaric discovered that Dr. Fell was using vampire blood to help patients...he also threatened to expose her practices to the council members.

The council members will be on a long list of those angry with Dr. Fell's use of vampire blood. In the season three finale we saw Damon's fury and confusion over Dr. Fell hiding Elena's cerebral hemorrhaging with vampire blood, but as actress Torrey DeVitto explains in an interview for the CW, it was something she had to do.

"Meredith felt the urge to help Elena and she did it the most efficient way she knew how," said DeVitto. "Giving her vampire blood."

DeVitto continued that her character knew that if she had brought up the use of vampire blood with Damon or Stefan, the brothers would have stopped her, causing Elena to die either way.

Torrey DeVitto kept a tight lip on what exactly Dr. Fell would be doing this season, but did reveal that she is "excited about the path she's going down."

"The Vampire Diaries" fourth season premieres on the CW on Thursday, Oct. 11.