You expect an excess of passion from a couple whose meet-cute moment involved an airborne plastic water bottle. But one insider claims Katy Perry and Russell Brand's hot-and-heavy romance has a tendency to get overheated, and that could spell trouble down the road. "They fight and make-up constantly," a "friend" of the popster alleges to the New York Daily News. "It's a cycle." One supposed point of contention between the lovebirds, who got engaged in India on New Year's Eve after three long months of togetherness: his onetime reputation as a "professional prostitute" (to use her term of endearment). "There have always been fights about other women," contends the source, "despite Russell talking about how much he loves Katy all the time." The couple, who are rumored to be getting hitched in the fall, spent the weekend apart, with Katy breaking out her bikini in the Bahamas and Russell slipping into a Batman costume while filming the "Arthur" remake in New York. "Hawt!" Perry approvingly tweeted of her newly clean-shaven fiancé's outfit, which makes us wonder about the paper's pot-stirring source, because if Katy can find Russell attractive in rubber, they're probably doing just fine.