Glenn (surname unknown, possibly Manlius if he took his husband's last name) was once the doctor on a USSA ship. Sandy fell in love with Glenn while watching him deliver an octoform's brood on Rigel 9. Some time later, they were married and Sandy was promoted to Captain of a USSA starcraft, the name of which is also unknown. Glenn was promoted to XO, as per USSA protocol that only married couples can be captain and XO.
After Jib Janeen, the Jupiter Spy infiltrated Mars, taking the forms of Sparks Nevada, Croach the Tracker, and Cactoid Jim amongst others, the USSA went to a star war with Jupiter over the matter. Sandy and Glenn's ship was specifically tasked with tracking down Jib Janeen. Unknown to Sandy and Glenn, Jib had managed to infiltrate their ship, and killed the former captain. His wife, the former XO, Antoinette Fontaine, had apparently gone mad with grief, but in actuality she had been frozen in carbonite and sold off, and Jib Janeen was pretending to be Fontaine.
Janeen-as-Fontaine convinced Sandy and Glenn to go to Mars, saying that he was sure the Jupiter Spy could be found there. Sandy beamed down to parlay with Sparks Nevada, but when he saw that The Red Plains Rider was in labor and needed a doctor, he beamed Glenn down to help, despite Glenn no longer being licensed to practice medicine. Glenn delivered Red's baby quickly and painlessly due to 30th century technology.
After Janeen took his baby and left, at some point he made his way back onto Sandy and Glenn's ship. He froze Sandy in Carbonite and sold him to the same aliens from planet XK9B to whom Fontaine was also sold.
Glenn mounted a rescue mission to get Sandy back after he fell into the hands of Chesh Glutterfane. Gutterfane enjoys collecting people who had been frozen in carbonite in order to lure their loved ones to his lair on planet X27991. The rescuers are forced to fight Glutterfane's monsters in arena combat, and his guests bet on the results. Unfortunately, Glenn failed to defeat his monster, but he managed to live. Gutterfane enslaved Glenn for several months.
Eventually, The Red Plains Rider arrived to save Cactoid Jim, who had also been captured by Jib, frozen and eventually sold to Glutterfane. Glenn tried to warn Red off, but she was determined. Red was given a child's weak gun and forced to fight an armor plated monster, but Red instead shot Glenn's slave control box off. Glenn, who was holding Red's gun, then turned the gun on Gutterfane. Red and Glenn rescued Jim and Sandy, along with several other slaves and their loved ones, and escaped on Gutterfane's pleasure barge.
In Sparks Nevada Vs Everything All Up At Once, Glenn has Sandy tell Sparks he sends his love before the end of the transmission when Sandy informs Sparks that invaders from unknown space with limited intellect, nefarious intention, and limitless greed are on a collision course with Mars, possibly to destroy the planet.