When Frank Dean discovered that his wife Leslie Dean had an affair with Jonah, PRIDE told Dale to inject him the Synnergy Serum so that he would forget everything about it. Years later however, Frank began to have flashes of memories he was supposed to forget when he personally encountered Jonah.
The serum was the subject of an article published in the American Journal of Experimental Medicine. The Minorus and the Yorkeses celebrated on this accomplishment and discussed the potential applications of the product, both in pharmaceutical and military areas.
Upon learning that Molly Hernandez could have witnessed the sacrifice of Destiny Gonzalez, Catherine Wilder considered using the Synnergy Serum on the teenager, although her husband Geoffrey advised her against it. Catherine took a syringe of the serum and later found Hernandez she took into her car. Catherine subtly interrogated Hernandez and prepared to inject her with the serum, but gave up on the idea when Hernandez gave her a plausible explanation about her presence in Geoffrey's office.
While the members of PRIDE were arguing about who should be sacrificed in order to revive Victor Stein, Dale and Stacey Yorkes mentioned the fact that the Synnergy Serum had been of great use to PRIDE and therefore that they were valuable for the organization.
PRIDE considered using an upgraded version of the serum on Graciela Aguirre to erase her memories of the evidence she could have regarding their criminal activities, although they never got the chance to do it and Aguirre was eventually killed by Tina. Arriving after the crime, the Runaways reclaimed a vial of the serum and later envisaged to use it on Topher as he had discovered the Hostel, although they eventually gave up on the idea.
PRIDE later repeatedly used the serum on Megan and Mary while testing the weapons they had been developing against the Runaways. This later caused Chase Stein to find a vial of the serum in the PRIDE Headquarters's bins.
The Synnergy Serum is manufactured in the form of small cartridges of blue liquid. The cartridges are then placed in a specifically designed syringe. Once the serum is injected, the subject's memories can be erased to a great extent, though the administered dosage can apparently be adjusted to moderate the effect resulting in the recipient losing recollection of only a few minute's worth of what transpired prior to receiving the dose. Dale Yorkes and Stacey Yorkes hypothesized that the serum could be used to treat PTSD for traumatized soldiers as well as reprogramming the mind of terrorists.
However, the effects of the serum were not absolute as it was too complicated to completely obliterate memories. As such, when Frank Dean, who had lost the memories of seeing his wife in bed with Jonah, encountered Jonah years after the event, he began experiencing memory flashes of the scene. In the end, Dean realized that what he saw in these flashes was real.
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