The pair, who hung out in Las Vegas the previous weekend, hit the clubs together in Los Angeles almost every night over the holiday week and even went shopping in Malibu together with Spears's son Sean Preston in tow on Saturday evening.
They kicked off their girl-time marathon on Tuesday, when Spears, 24, went to a post-American Music Awards party Hilton, 25, hosted at her West Hollywood home. The following night, they were spotted at Teddy's at the Roosevelt Hotel in matching leopard-print outfits. (Spears's estranged husband, Kevin Federline, was hosting an album party across town at Republic the same night.)
On Friday, Hilton left her sister Nicky and friends at the nightclub Les Deux to pick up Spears. The pair stopped at Hyde Lounge before eventually heading back to Les Deux just before close.
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"Paris was acting like Britney's boyfriend," says a source who saw them at Hyde on Friday. "She opened doors for her, held her hand, and even had her arm around Britney's lower back. Britney happily accepted Paris' friendly gestures."
Spears filed for divorce from Federline earlier on Nov. 7 after two years of marriage.