The BBC Three drama's fifth series begins this Sunday (February 3) at 10pm.
Damien Molony (Hal) told DS that the "bromance" between his character and Michael Socha's Tom will be tested in the new episodes.
"Tom and Hal grow from strength to strength," said the Irish actor. "[But] a lot of obstacles are thrown our way by various individuals to try and break that up!"
Socha agreed, saying: "Essentially they are best friends... but it really does get tested in this series."
Whitechapel's Phil Davis will play new villain Captain Hatch, and revealed that he was attracted to Being Human by its combination of "gory horror and very hip, funny badinage".
"He's a very nasty, spiteful, disgusting old man," Davis said of his role. "What he needs... to get his powers back is for a vampire and a werewolf to be set against each other - so he tries to stir them up!"
> Being Human: Ten teasers about Series Five premiere 'The Trinity'
[Gallery: 'Being Human' Series five premiere 'The Trinity' in pictures:]
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