Much like the great majority of Science Police officers, Shvaughn was dedicated to her job, believing that they were a force for good in the galaxy. Imagine her disdain, then, when the Legion of Super-Heroes was formed, and, it seemed, had come to steal their thunder while being just a bunch of show-off celebrities. She held Leviathan, in particular, in contempt; how could anyone resign from the Science Police to join the Legion?
It didn't help that, during an argument with Leviathan, she was attacked by the Composite Man and got her back broken.
Shvaughn Erin was given the job of Legion/SP liaison as only her second job out of the Science Police Academy, after a short period of clerking under Commander Hagbard where she first encountered the then-SP Cadet Imra Ardeen.
Initially angered by the desk job, and further enraged by the taunting of her colleagues who promptly dubbed her "Liason Lass", she grew to accept the assignment after studying the Legionnaires' files. She was particularly impressed by XS, Kinetix, and ironically enough, Leviathan's files, especially after she learned that he had resigned because his commanding officer was merely using him to further his image and career, and was more interested in that than even his men's lives.
Shvaughn quickly became a loyal ally to the Legionnaires, offering condolences during Apparition's and Andromeda's funerals and trying to keep the Science Police out of a Legion Headquarters that had been destroyed after Brainiac 5 had experimented with time travel. She even successfully defended the headquarters against an invasion of semi-sentient shapeshifting beings who were trying to use an acid bomb to destroy the building's power generator - an act which, had it been successful, would have destroyed the entire city of Metropolis. Luckily, Shvaughn and the Legion support staff came through.
She next aided the Legion again when the Emerald Eye had taken over Shrinking Violet; Shvaughn briefly shattered the Eye, but was turned into a baby in retaliation. This didn't keep her down though; she joined Saturn Girl, Apparition and Inferno in an assault on the satellite Violet had taken over. They were able to spur Violet into leaving, but Shvaughn and the others were thrown back in time to the 20th century.
It was during this time that the age gap between her and the Legionnaires became apparent. Although only a few years older, Shvaughn was still an adult and more mature than the Legionnaires, and so felt a little left out at times. To keep sane, she kept a computer journal of all the Legionnaires, their missions and even their day-to-day interactions. She also bonded with Ultra Boy, to the then-permanently intangible Apparition's intense jealousy.
Shvaughn remained a staunch ally and friend of the Legion's, though, and took part in many missions: meeting Superman, helping against the Final Night and tracking down Doctor Psycho after he attacked Saturn Girl. She was also the one who figured out that Saturn Girl had been unconsciously taking mental control of the body of a still-comatose Cosmic Boy. Her journal, though, proved a liability as C.O.M.P.U.T.O. was able to download these and use the information therein against the Legionnaires.
After C.O.M.P.U.T.O. was defeated, though, Shvaughn accompanied the team back to the 30th century.
Upon their return, Shvaughn was quickly promoted to Lieutenant for helping the Legion on their "secret mission". This was a promotion that her friends in the Legion gladly celebrated with her. Shvaughn also helped convince Leland McCauley to drop criminal charges against Karate Kid after the latter had severely damaged his property, leading top Karate Kid joining the Legion. She also helped a team of Legionnaires get to Durla to reunite with Chameleon during the Dark Circle crisis, and helped the team disarm and neutralize the invading soldiers when time had stopped.
Despite not having any powers, her Science Police training enabled her to remain one of the last free resistance fighters when the Blight invaded Earth. She, along with Live Wire, XS and Chameleon, were escorting a batch of refugees to safety when they were suddenly attacked by the Blight, and she was among those captured and taken into the Stem, the Blight's base of operations. To her credit, she remained conscious almost as long as XS did. She was later freed and reunited with her friends after the Blight were defeated.
Things might have turned out better, had the Legion not been disbanded after the Great Rift Disaster. Although missing the good times, she returned to her work with the Science Police, actively encouraging Dyrk Magz (formerly Magno), and inadvertently spurring Kinetix to join their ranks. She also worked with M'Onel to investigate the odd mechanism that Tharok had been carrying when he re-entered Earth's atmosphere. However, that thing, which was actually an envoy of the Robotican race, suddenly "infected" the lab they were working in, deleting a fellow officer, and might have spread all over the Earth had they not worked quickly to destroy it.
After the Legion had reformed, Shvaughn was glad to work with them again. However, this led to another short ordeal as she was trapped on Earth with Brainiac 5 and Kinetix, the latter recently having become a Terrorform hybrid, when Robotica "downloaded" themselves onto Earth and swarmed the whole planet. The trio were almost able to reach the Threshold to Legion World, but were unable to prevent Brainy's capture, much to Shvaughn's dismay. Later, after Kinetix was starting to transform again to become more like the Roboticans, Shvaughn was able to get her to open a gap in the shield the Roboticans had erected around the Earth, letting a Legion strike team in in the process.
She would later accompany Ra's al Ghul's prison guard to Legion World in a bid to get him to save Sensor's life after she had been caught in a wave of hypertaxis energy. Unfortunately, she was unable to prevent Ra's escape and would have been killed had it not been for M'Onel.