Ever since Jonathan Frakes played the first officer of the USS Enterprise-D Will Riker, Frakes has gone on to appear in almost every Star Trek series since, albeit as transporter accident-spawned clone Thomas Riker in Deep Space Nine. Usually, fans love to see the adventurous Riker swing into a guest appearance on another series. But that wasn’t the case when Riker and Deanna Troi (Marina Sirtis) showed up in the series finale of Star Trek: Enterprise.

“It was sold as, ‘Oh, come on and do the episode, it will be a Valentine to the fans,’” Frakes told Variety when recalling his appearance in that show’s series finale. As the last episode in a continuous run of Star Trek series that began with Star Trek: The Next Generation in 1987, the Enterprise finale “These Are the Voyages…” sought to connect the end to the beginning. And so the episode follows not Scott Bakula’s Captain Archer and his crew, but Riker, who visits the NX-01 in a holodeck program.

Enterprise has always been the least popular of the four ’90s Trek series, stumbling for its first few seasons, as did every entry in that franchise era. But by season four, Enterprise had really found its footing. The Xindi Incident storyline connected the show to the audience’s post-9/11 malaise and gave the series a tighter, more exciting storyline. Yet, where all other series of the era ran for seven seasons, Enterprise was cut off at four, kneecapping it just as it started to get good. Focusing the finale on Riker instead of Archer and the rest of his crew, and unceremoniously killing off fan favorite Trip Tucker (Connor Trinneer), “These Are the Voyages…” showed no respect to those who stuck with the series.

“[I]t wasn’t a Valentine to the fans,” Frakes now admits. “The fans didn’t want to see us.” Even though he feels that “These Are the Voyages…” was “a good episode” and that he “had a blast doing it in many ways,” Frakes acknowledges that fans felt betrayed by the bait and switch. “The more I think about it, the more I hear from fans about it in particular, it may not have been the best choice we’ve made on Star Trek.”