Dilemmas will abound when “The Vampire Diaries” returns with six new episodes Thursday on the CW. The Klaus Chapter, as executive producer Julie Plec has dubbed the final episodes of the season, will be full of challenges and choices, not to mention some possible character deaths. As the series prepares to introduce the much-talked-about Klaus (Joseph Morgan), the biggest dilemma facing Elena (Nina Dobrev) and her friends will be figuring out how to kill the Original vampire before he can sacrifice her. They already know of one way to do the trick using the white oak ash-dipped dagger, but there’s just one problem: The dagger is embedded in Elijah (Daniel Gillies), and taking it out would mean letting him come back to undead life.

“There’s one weapon, two originals. I wonder what’s going to happen,” Plec mused coyly during an interview with Showtracker. “That is their big conundrum. As soon as we get back from the hiatus, we’re going to start asking that question and seeing what our characters decide to do about it will be pretty big.”

Deciding how to handle the ritual and best protect Elena will cause tension between Stefan (Paul Wesley) and Damon (Ian Somerhalder), who have a difference of opinion on the matter. (Elena’s biological parents, John (David Anders) and Isobel (Mia Kirshner), also put in their own two cents.) “Damon will stop at nothing to insure Elena’s survival,” said Plec. “Stefan is sort more willing to let Elena have a voice in the process. Damon doesn’t necessarily like what Elena has to say.” But just because he doesn’t like what she has to say doesn’t mean Damon’s actions aren’t loaded with feelings for Elena. Stefan not only will have to deal with the fact that his girlfriend could die — “The threat that Elena might not live to see her 18th birthday is definitely weighing heavily on them,” teased Plec — but also his girlfriend and brother’s growing closeness.

“Damon and Elena’s closeness is a big obstacle in Stefan and Elena’s relationship,” said Plec. “Not because of how Stefan feels about it because he’s fully aware that Damon has feelings for Elena. It’s the decisions Damon makes and the actions Damon takes to protect Elena, which are in direct conflict often with the way Stefan would like the situation to be handled.

“Stefan is in the ultimate predicament, which is that he has this wonderfully solid, beautiful love story with Elena, but he’s also got a very complicated love story with his brother. So when he’s trying to achieve both relationships successfully, there’s always going to be a problem of ‘I can’t kick my brother’s ass because he’s after my girl without losing my relationship with my brother, but I’m not going to let my brother go after my girl.’ ”

Relationship issues will also be plaguing Caroline (Candice Accola) and Matt (Zach Roerig), who’s now in the know about the town’s vampires. “The future is complicated for them,” shared Plec. “When we first come back from hiatus, the very first question is, ‘How is he going to ultimately handle this information, and what is Caroline going to do about it?’ And the answer to that, which is in the first episode back, really sets the stage for some big relationship issues that will take us to the end of the season.” And then there’s the inevitable return of Tyler (Michael Trevino), who’s got his own stake in the Caroline-Matt relationship. “We can’t have a triangle without your third point. So one day, we will be seeing Tyler again.”