The Real Housewives of Beverly Hills star, 58, worked with Locklear, 59, on the long-running soap opera Melrose Place in the late 1990s. When Rinna joined the show in 1996, five seasons had already aired, four of which starred Locklear.
On this week's episode of PEOPLE in the '90s, Rinna told co-hosts Andrea Lavinthal and Jason Sheeler that joining the iconic series several seasons in had her "scared s---less," though Locklear helped ease her fears.
"It's never fun to be the new girl coming into a very popular, established show," she said. "It's scary, scary, scary. But starting from the top, Heather Locklear could not have been nicer and more welcoming, which then sets the tone. I always felt very welcomed there and really good, and that's all due to Heather."
And while she and Locklear didn't spend much time together off-set, Rinna said the Dynasty alum taught her a lot about acting.
"Heather and I had a great relationship, and she just was such a star," she recalled. "I learned so much from Heather Locklear, probably more than anybody. I learned a lot from Heather and I learned a lot from Jason Bateman when I did The Hogan Family for six episodes. Two of the most professional, talented people in this business. What I learned from them is what I take into my professional life and what I have shared with my daughters to this day. They are true pros."
"And so Heather and I had a great time. I mean, we weren't best friends off-camera — we didn't hang out every minute," she continued. "We were actors that worked together that really respected one another and allowed each other to have the space to play, and it was just a brilliant experience for me."
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Rinna also said she "loved" the exaggerated drama and her character, Taylor McBride.
"What a juicy role to get to play. I look back at it and I can't even believe that that was allowed and that we got to do that, and I got to dress the way I did, and the fights and getting slapped by Peter," she said, referring to Jack Wagner's character. "All the things that happened, we couldn't do that today, I don't think."
Asked about her most "surreal" '90s moment, Rinna replied, "Having an affair with the guy who played my brother."
"Well, not an affair, but a couple of one-night stands with the guy who [played] my brother. Patrick Muldoon and I had like, a thing," she continued, clarifying that it was before she met now-husband Harry Hamlin.
Rinna played Billie Reed on Days of Our Lives from 1992 to 1995, during which time Muldoon, 52, played her onscreen brother, Austin Reed. Since their exits, the two have returned several times to reprise their roles on the long-running show. Like Rinna, Muldoon also went on to star in Melrose Place.