UFC is a little misleading on the role with Chuck Liddell in Pride.
Chuck Liddell actually had 5 fights before even fighting his 1st fight in Pride. At the time, the UFC and Pride had a friendly competition, and the UFC allowed Chuck to go over to Pride to compete to *allegedly* show that UFC fighters were better than Pride fighters.
After Chuck had gone 7-1 (4-1 in the UFC), he fought Guy Mezger at Pride 14, and soundedly defeated him with knockout in the 2nd round.
Chuck then returned to the UFC, where he went 4-1, with his last fight losing to Randy Couture. He then returned to Pride for 2 more fights.
In his 2nd Pride fight, he KO'd Alistair Overeem in about 3 minutes. In his 3rd Pride fight, he met the man who would become his archnemesis.. Quinton "Rampage" Jackson. Chuck was being dominated through the whole fight, and his corner threw in the towel 3 minutes into the 2nd round because was taking a beating so bad. Chuck went 2-1 in Pride, and was actually encouraged to fight there by Dana White and the UFC.
3 years after that fight, UFC started to boom in popularity, and bought out Pride. Rumor is because they saw them as a threat, and they had the money to do so then.
Meanwhile, back in the UFC.. Chuck continued his domination, going 7-0 defeating Tito Ortiz (2x), Vernon White, Babalu, and avenging his only two losses in the UFC against Randy Couture (2x) and Jeremy Horn. And then was the acquisition of Pride.. Chuck was at the top of his game, Rampage won his UFC debut against Marvin Eastman, which prompted him a title shot (for some reason) against his nemesis, Chuck Liddell (Chuck supposedly asked for this fight, because he wanted to avenge his last loss).
As UFC fans know, Rampage knocked out Chuck Liddell in less than 2 minutes.. thus starting the downfall of Chuck Liddell. After that loss, Chuck went on to a 1-3 record in the next 4 fights, losing to Keith Jardine by split decision, edging out a decision win against Wanderlei Silva, and getting knocked out by both Rashad Evans and Shogun Rua.
Chuck has not fought since his KO loss to Shogun early last year. Dana claiming he has retired, but Chuck was thinking otherwise. It was announced a few months back that Chuck Liddell and Tito Ortiz will each be coaches on the next Ultimate Fighter, prompting a Chuck Liddell vs. Tito Ortiz III at the end of the season.
Just a little history of Chuck Liddell and his role in Pride.