WHAT do Kevin Costner and Bob Fontenot have in common? Not a lot at face value, seeing as the latter stands 1.9 m tall (6ft 3ins), weighs in at 181 kg and doesn't take direction. But they have both taken good care of Whitney Houston, even if only one does it for real. That's right, Bob Fontenot is the bodyguard. ''Sure, I saw the movie, and I liked it,'' said the 26-year-old man-mountain from Los Angeles. ''I like the job because it means I can travel and meet different people . . . but I'm not really fascinated by the celebrities.'' Fontenot has been in security for six years, and with Bobby Brown for two and a half. Then along came the missus. ''I mainly stay with Bobby, but when she comes along, he likes me to stay with her,'' he said. ''She's a nice person.'' And one who is in constant demand. Although Hongkong didn't throw up any problems, there was an altercation in Singapore when Fontenot was alleged to have threatened press photographers. ''The press were a little rude,'' countered Fontenot. ''We asked if they would step back but they didn't. You have to try to be diplomatic, but . . .''