Chris Meloni: My 'True Blood' vampire is 'a big old baby' John P. Johnson / HBO Christopher Meloni stars as vampire Roman on "True Blood." After playing detective Elliot Stabler on "Law and Order: SVU" for more than a decade, Christopher Meloni has hung up his detective badge and replaced it with a set of vampire fangs. The Emmy-nominated actor joins HBO's "True Blood" this season as Roman, a powerful, 500-year-old vampire who sits at the head of the table of the Vampire Authority. Roman's main mission is to get his blood-drinking brethren to cohabitate peacefully with humans. Meloni, who will make his first appearance on the show in season 5"s second episode (airing June 17), tells The Hollywood Reporter that Roman's driving force is "the rightness of his cause." Photos from THR: 'True Blood' season five "His unbending drive to get what he wants," says Meloni, who spoke to THR from the set of the upcoming Jackie Robinson biopic, "42," in which he plays Brooklyn Dodger manager Leo Durocher. I think on the outside if you're with him, you agree and you want to follow someone like that. If you disagree, then you think he's a fanatic. Although Roman may be one of the older vampires in town, Meloni says his character isn't as wise as his years. You know who acts like that? A child," he says. And I thought that was what kind of funny about it. Here you have this very impressive entity, yet underneath it all, he's a big old baby. "But don't tell him that to his face," he adds. Video from THR: 'True Blood' season five teaser Features Christopher Meloni, the new Tara Meloni, who in May 2011 announced that he would not return to NBC's "Law and Order: SVU" for its 13th season, tells THR that he has always been a fan of "True Blood" showrunner Alan Ball, and enjoyed being the guest, rather than the host, of a show. "I was now the guest after having a decade of witnessing people being guests on my show," he said. I got a kick out of that. It was a lot of fun to see how another set was run. Roman and the Vampire Authority introduce a complication to the already-complicated HBO drama. When vampire Eric (Alexander Skarsgard) and Bill (Stephen Moyer) kill Nan Flanagan (Jessica Tuck), a member of the vampire authority, they are hunted down by the vampire government. This results in Roman holding the fates of Bill and Eric in his already-bloodstained hands. Meloni's first scene was one of the tougher for him to shoot, he says, because he was "trying on this new person, this new thing." "You can do all the preparation you want, but at least I kind of find my character along the way," he said. More from THR: 5 key moments from 'True Blood's' season premiere "True Blood" is known for his supernatural drama, and it's heavy-dose of sex scenes, which can range from slightly strange to extremely twisted. Fans of Meloni have been wondering if his character will get to do any bed hopping this season. Meloni, who will also appear in Zack Snyder's Super Man reboot "Man of Steel," tells THR he wasn't sure if he could reveal that particular piece of information, but did hint, "I am in bed. With my lover. As always with the HBO vampire drama, hints about what could be coming up in the show were few and far between. However, Meloni, did say a scene involving a possible traitor in the Authority was some of his favorite work on the show. That was a lot of fun. It's what I signed on to do," he said. What's your favorite thing about season five so far?