Gabriel Sitter is a Physics major with a focus in Quantum Physics.  Gabriel's studies led him to join the junior team of the Ghostbusters.
Gabriel Sitter majored full-time in Quantum Physics for his Bachelor of the Arts. He became interested in ghosts only so far as their connection to the harder sciences and wanted to be able to explain them to people by way of quantum physics. He got a part time job with the Ghostbusters to study the connections and help pay for school. Since accepting the position, he grew to appreciate the differences between the natural and supernatural sciences. He even built up a friendly rivalry with Samuel Hazer over which is more important to the world at large. Gabriel was fascinated with the P.K.E. readings given off by the Cerberus Manifestation. Alan Crendall wanted to draw it away from Bridget before they attacked it. Gabriel realized it was gone. Gabriel helped trap all of Connla's Army on Liberty Island in the prime dimension weeks away from Halloween. When Egon Spengler mentioned Mike the Golem was from "The Village," Gabriel got excited and misinterpreted it as a Golem village. He wanted to hear all about it when they were done then asked when that would be. Egon Spengler of Dimension 68-R, Abby Yates of Dimension 80-C and Roland Jackson of Dimension 68-E checked their P.K.E. Meters and verified all the ghosts were captured. Egon Spengler, of the prime dimension, asked the Ghostbusters junior team for their help in retrieving ghosts that escaped from the Containment Unit and escaped into the multiverse. All of the teams involved in the operation gathered in the Warehouse.
Gabriel spoke up and Samuel asked why they didn't just use the Interspatial Teleportation Unit to go back in time and prevent the incident from happening. Gabriel agreed with Samuel but noted time travel backfired for the Flash on TV. Ray replied there was no time travel component. The Extreme Ghostbusters chimed in the Egon on The Real Ghostbusters of Dimension 68-R looked like a younger version of their Egon. Gabriel wondered why they didn't let them use the teleportation unit to recruit help back when Dumazu was a threat. The prime dimension's Egon reiterated the teleportation unit could not time travel but time was a dimension they could access in so far as they went to parallel realities that could be further ahead or further behind what they knew as the present but no action they took had an effect on their timeline.
A field team consisting of Ray Stantz of Dimension 68-R, Gabriel Sitter of 50-S, Janine Melnitz, Ron Alexander, Patty Tolan of 80-C, and Garrett Miller of 68-E arrived in a parallel dimension. They canvassed a circus but Garrett was possessed by the Hungry Manitou and it generated a Giant Murder Clown construct around themselves for protection while it fed. Ron used a Proton Grenade despite Janine's objection. The Murder Clown retaliated and fired deadly projectiles that resembled ice cream cones. Ray 68-R and Gabriel wondered why he wasn't fired yet. Janine stated they wanted him where they could keep an eye on him and were waiting for memory erasing technology to be perfected by Egon. Ron quipped it would never be finished since Egon tested it on himself and they didn't want him selling everything he knew to the highest bidder. Ron was stopped mid-sentence and realized three of the Murder Clown's projectiles had pierced his chest and stomach then he fell over.
The remaining Ghostbusters opened fire on the Murder Clown while Ron threatened to sue. Gabriel was sure no major organs were pierced but he needed to get to a hospital as soon as possible. Janine told Gabriel her Ghostbusters captured the Manitou in Schenectady and it wanted to eat them, not kill them right away. Gabriel hoped she meant that as a euphemism. The Giant Murder Clown wasn't weakening. Janine knew they needed something else. Ron came to and told Gabriel to cut his Proton Pack off and call the "fat guy" over. Gabriel assumed he was talking about Ray 68-R. At first, he didn't get it but Ron explained the Proton Grenade stunned it but blowing up the Proton Pack would be strong enough to free Garrett. Ray 68-R threw the pack into the air and ordered everyone to shoot it. The explosion dispersed the Giant Murder Clown and freed Garrett. The Manitou was angered. It decided to forgo its hunger and kill everyone. Garrett blasted it mid-charge. Patty prompted Gabriel, as "uptight guy," to throw out a Trap-Gate. Gabriel threw out his Trap-Gate and corrected her that he was cautious then captured the Manitou. He believed they did relatively well since they only used two Traps. Patty and Janine disagreed. The field teams were whisked away by Tiamat to the Collectors' Limbo. Rather than serve her, they fought back. Gabriel took readings and ascertained she was powerful and he suspected she was evil. Bridget thought that was already obvious. She could feel the bad vibes for days. Tiamat was stripped of her P.K.E and trapped.
Upon returning to their home dimension, the team requested time off. Peter was aghast. Alan explained they just got through chasing ghosts in other dimensions, fighting Tiamat in the Collectors' Limbo, and saving the multiverse. Gabriel felt they deserved a day off. Peter wasn't impressed and reminded them his team also saved the multiverse before. Ray added they did so at least a dozen times. Peter recalled they also got paid for it each time. Janine interceded and announced there was a call about a haunted house that appeared out of nowhere in Bayside, Queens. Peter assigned the case to the SOS team. Gabriel Sitter registered high readings off the house with his P.K.E. Meter, Bridget got serious bad vibes from it, and even Alan felt something was off. Alan charged the door. An old woman asked what they were doing, but they quickly forced her hand and she revealed she was Wat then attacked them with lightning blasts. She raised them up towards the ceiling. Gabriel reached for his Pocket-Sized Grenade and tossed it at Wat. Wat was dazed and presented an opening. Samuel threw out a Trap and thought he trapped Wat. However, Wat hid itself on Alan's flight suit. After researching Wat for an hour at the New York City Public Library, they were driven back to the Firehouse by Geoff. Gabriel thanked him for bringing their gear along. Geoff was happy to oblige then retreated to safety.
Gabriel checked his P.K.E. Meter and confirmed there was an active presence inside. Alan addressed Wat. He refused to give up. They opened fire but he manifested in his true form. The SOS team and Egon quickly ran out of the Firehouse. Wat burst through the firehall and chased after them. Gabriel noted while Wat was powerful, it still had the right energy profile to be trapped. Egon contended the Traps currently lacked enough power to do so. Alan pointed out they lived in a major city and there was power everywhere. He tasked Gabriel and Egon with tapping into a utility box for the extra power while everyone else tried to distract Wat. Egon cautioned Gabriel what they were doing was highly dangerous. Gabriel thought it wasn't as bad as shooting at a dinosaur or crossing the streams but he then realized they didn't have enough cable to take the Trap to the others. He hailed Alan on comms but Alan was pinned in Wat's jaws. Gabriel asked Alan to lure Wat to them in the alley. Alan couldn't believe it. Wat clamped down on Alan. Alan fired his thrower, blew up Wat's head, and ran for it. The headless Wat chased after them. Egon gave Gabriel the signal and he trapped Wat. They celebrated the win but the ordeal triggered a city-wide black out. He asked Egon to tell the others it was Samuel's fault.
After a case at the Calvin Home on Staten Island went off the rails, Bridget retreated and called in Samuel and Gabriel. They trapped a Sandman then Alan regained consciousness soon after. Gabriel apprised Alan of the situation.
"The technical genius of the group, he's also not scared of getting his hands dirty when the ghosts try and get up close and personal. Following in Dr. Spengler's footsteps, he's keen to learn more about being a Ghostbuster, and make his own mark unearthing more information on the spectral realm and developing his own new technologies." 
- On page 21 of Ghostbusters Crossing Over Issue #6, Gabriel's biography mentions his study of quantum physics and interest in the connection between the supernatural and natural sciences. Samuel's biography mentions he and Gabriel often debate about the most effective way to deal with ghosts.
- Gabriel's photo is from Ghostbusters Get Real Issue #3, page 9, panel 2.
- Ghostbusters Get Real
- Ghostbusters Annual 2017
- Answering The Call
- Ghostbusters Annual 2018
- Ghostbusters Crossing Over
- Ghostbusters IDW 20/20
- IDW 20/20
- Down the Basement Stairs
- ↑ http://protoncharging.com/gb/2011/02/16/sanctum-of-slime-dev-diary-and-three-new-screens/
- ↑ Level 1 Dialogue
- ↑ Narrator (2019). IDW Comics- "Ghostbusters IDW 20/20" (2019) (Comic dramatis personae page). Narrator says: "A part-time Ghostbuster and full-time student, Gabe was mostly interested in a job with the Ghostbusters to learn how ghosts related to the hard sciences."
- ↑ TomWaltz Tweet 5/8/18
- ↑ http://content.usatoday.com/communities/gamehunters/post/2011/02/first-look-get-to-know-two-more-ghostbusters-rookies/1
- ↑ 50-S Memo (2018). IDW Comics- "Ghostbusters Crossing Over Issue #6" (2018) (Comic p.21). 50-S Memo reads: "Gabriel Sitter; a tech-head and quantum physics student whose interest in the paranormal is to square it with his field. He wants to measure and test spectral material to a degree that no even Egon Spengler has."
- ↑ 50-S Memo (2018). IDW Comics- "Ghostbusters Crossing Over Issue #6" (2018) (Comic p.21). 50-S Memo reads: "A parapsychology student who has a love of the lore that almost rivals Ray Stantz. He is a firm believer in magic and often debates colleague Gabe Sitter over the most effective way to deal with ghosts."