Nina Dobrev, Ian Somerhalder Pack on PDA at Comic-Con

Vampires in love?

Vampires Diaries' costars Nina Dobrev and Ian Somerhalder were all over each other at Comic-Con in San Diego over the weekend.

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On Friday, a source told Us Weekly the duo were "inseparable" at the Maxim, FX and Fox Entertainment Party. "He was very protective of her, and brought her a couple of cocktails from the bar," the insider added. "When she went to the bathroom -- and it appeared they were ready to leave -- he waited patiently outside the restroom and smiled at her when she exited. From there, they stood by the elevator and said goodbye to friends before heading to the Hilton Bayfront where they were seen heading to the hotel bar."

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The same night, at the Camp Playboy bash, Somerhalder, 32, paid special attention to Nina."

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He reportedly stroked the 22-year-old's hair on numerous occasions in between making out with her. Dobrev "kept playing with his hat and lifting it off his head to get his attention," said a source. "She [also] stroked his hair."