On the BBC fantasy drama, the king of Camelot (James) remains ignorant of the special powers possessed by his wizard friend (Colin Morgan).
"He's well ready [to learn the truth]," the actor told TV Choice. "It's something that - because of the dynamic of the show - the creators are probably wanting to hold onto.
"It's worked in the past, and that's effectively the tease for the audience. But I'm hoping that it doesn't go on too much longer... we'll see."
However, James added that he is pleased with how the storytelling on Merlin has evolved, suggesting that the show has "become more about political wars, as opposed to fighting mythical creatures".
"I think shows like this need to develop, and that's what's happened," he said. "Otherwise, it can get stale and audiences switch off, but that hasn't happened. The audiences have grown for us, so we've been very fortunate."
The 28-year-old recently told Digital Spy that he would be happy to make a sixth series of Merlin "if everyone still has the passion for it".
"We've got two weeks left of filming [on series five], we'll all get a break and see how we feel," he explained. "When the passion goes, that's when you need to stop."
Merlin continues this Saturday (October 13) at 8.25pm on BBC One.
> Merlin: Ten teasers about 'Arthur's Bane (Part Two)'
> Merlin: How dark is too dark for the BBC fantasy drama?
Watch a trailer for the next episode of Merlin below: