|Books character||TV character|
He is a small man with salt-and-pepper hair, and Chinese features.
At the age of eight, Prax's father had transferred from Europa to Ganymede to build a research lab. Ten years later when his family signed a new contract and moved to an asteroid near Neptune, Prax stayed on Ganymede, where he has lived for thirty years. He got a botany internship in hopes of growing marijuana but realized a third of botany students had the same plan.
He was formerly married to Nicola Mulko with whom he had Mei.
For the last eight years Prax's life he has been working the Glycine kenon, a heavily modified, low-resource, soybean.
During the Ganymede incident Prax is in his greenhouse with Dr. Doris Bourne. As the mirrors in orbit begin their decent onto the moon, Doris urges Prax to leave. After Prax grabs one of his soybeans, the two get into the lift as the mirrors and other debris hit the moon and greenhouse. The power shuts off and back on again, then the two make their escape.
Leaving the greenhouse he proceeded to his daughter, Mei's, daycare. He was stopped by soldiers who tell him that all access to the tube station is closed until the fighting has stopped. Having an intimate knowledge of the layout of Ganymede, Prax found a scooter in one of the maintenance sections. He then proceeded to the daycare avoiding soldiers and gunfire. Once he arrived, Miss Carrie, the teacher, tells him that Mei has already been picked up by her mother. Knowing that Nicola was living on Ceres and that she couldn't have picked up Mei he realizes his daughter has been kidnapped. At this early point, nobody is aware of involvement from anyone other than his ex-wife's imposter so, Prax's fears are compounded by a possible medical tragedy.
In the week since Mei's disappearance Prax has developed a routine of places to look at people to talk to. He goes to visit Basia Merton the father of a child with Myer's disease for the fifth time. He tells Prax that he and his family are leaving without finding their son Katoa Merton who is also missing. This angers Prax and they get into a physical altercation disrupted with Basia's daughter, Felcia, intervening to stop her father from beating Prax to death.
Later, Prax contacts a hacker to penetrate the station's security in order to find video feeds of whoever took his daughter in exchange for a small salad, all the food he has. He soon discovered that Dr. Strickland and an unknown woman are the ones who took Mei. He then has hope that Mei is still alive due to Dr. Strickland's awareness of her condition. When Prax asks the hacker if he can follow the trail of feeds along further to see where they went from there, the boy raises the price to a chicken. Not having any, Prax is left no choice but to head home. With the newly acquired knowledge of Strickland's involvement, he then compiles a list of all the children in Mei's therapy group remembering sixteen of the twenty children. With this list, he visits the security center and asks about the children to learn that all sixteen of them are missing. It's then that he realizes what poor condition he is in, having not eaten or exercised in days. He then proceeds to the relief center where he finds himself in the middle of a food riot. It is there that he recognizes a familiar face that he doesn't identify immediately, the face of Jim Holden.
The Weeping Somnambulist
Prax, Holden, and Naomi Nagata make their way back to the Weeping Somnambulist where Prax tells them his story. While Amos Burton does recon and gathers supplies, Holden forces Prax to eat a meal and take a shower. Amos returns with a case of canned "chicken food products" which Holden hopes the hacker that Prax hired will take as a token of payment. Then, Holden, Amos, and Prax make their way to the hacker while Naomi monitors them from the ship. They arrive at the hacker's home for the exchange, but the hacker believes they have more chicken and attempts to extort a higher price. Instead, Amos begins to beat the hacker with one of the cans, eventually being called off by Holden when the hacker agrees to help them. The hacker shows them the footage of Mei being taken by her doctor and another woman whom Prax doesn't recognize, but the school's security registered as Mei's mother. The footage follows them up to an old utility storage area (from before the station was finished) that the security feeds do not follow. They leave the case of chicken with the hacker as payment and head back to the ship. With Naomi, they discuss a plan: Naomi will monitor them and take care of any electronic threats, Prax will be there for Mei to recognize and to give any details on her illness that affects the rescue, leaving Holden and Amos to the violence.
Here There Be Dragons
As the three of them head through to tunnels to find Mei, they are stopped by a group of six former Pinkwater Security, led by a man named Wendell. They try to pinch the trio for 100 Martian scrip or 500 local currency. Holden is able to talk them down and when they recognize him, Jim convinces them to join the their rescue party. In exchange for getting Wendell's group off Ganymede, they agree to help in the raid to recover Mei. The joint group arrives at the doorway where surveillance footage had lost track of Mei and together they begin clearing the tunnels. During their search, they come across the dead body of Katoa Merton. Filled with anger, Prax opens the next door to find a group of security guards taking a break. Prax, hysterical, inadvertently starts a gunfight which the rest of his group narrowly manages to cover without further friendly losses. The group presses on and finds more security guards and a secret science lab with the black tendrils of the Protomolecule. Holden then calls Naomi telling her they have to leave immediately.
Holden gives the Somnambulist to Wendell and his remaining Pinkwater Security crew so they can immediately evacuate Ganymede while the others will use the Rocinante; however, they are ambushed and briefly held captive by a UN detail.
|“||It’s the basic obstacle of artificial ecosystems. In a normal evolutionary environment, there’s enough diversity to cushion the system when something catastrophic happens. That’s nature. Catastrophic things happen all the time. But nothing we can build has the depth. One thing goes wrong, and there’s only a few compensatory pathways that can step in. They get overstressed. Fall out of balance. When the next one fails, there are even fewer paths, and then they’re more stressed. It’s a simple complex system. That’s the technical name for it. Because it’s simple, it’s prone to cascades, and because it’s complex, you can’t predict what’s going to fail. Or how. It’s computationally impossible.||„|
|— Praxidike Meng|
in describing a 'cascade'
The Monster and The Rocket
When a protomolecule hybrid is discovered as a stowaway in the cargo hold of the Rocinante, it is Prax who devises a radioactive bait to lead the creature out into space where the exhaust of the ship can destroy the monster.
Once Rocinante is back at Tycho station, Prax contacts Basia to inform him of Katoa's recent death. Prax contacts a private investigation company in the hopes of applying to contract the search for Mei. He contacts his ex-wife, Nicola Mulko, asking for some contribution which she ultimately sends the equivalent of a week of pay. When the price comes through, he realizes he simply will never be able to fund the project.
Upon discussing the cost with Holden and crew, they're somewhat disappointed that he didn't anticipate the crew of Rocinante was already on the job especially since Fred Johnson has just fired Holden's crew and they are now independent of the OPA. Of course, the funds to pay for expenses would still need to be attained. They resolve to create a crowd-source funding project and have Naomi compose an appeal video. 
After sleeping Prax awakens to a big breakfast where he explains to Amos how he could tell the beef is "vat-grown" and, "You can tell from the way the muscle fibers grow [layered]."
Widespread responses overnight to the appeal video provide the needed budget with many supportive messages some of which seem to be seeking romance. There's also a message from a Dr Moynahan that reveals Dr Strickland's past as a bio researcher for Protogen named Carlos Merrian who Moynahan met at Ceres Mining & Tech University.
Further investigation and analysis of tariff records determines that the most likely escape destination for Doctor Strickland's secret protomolecule research project is a station on the Jovian moon Io. Rocinante makes way on a heading there.
As quickly as the account balance had welled up, there's a sudden turn. Someone has coerced Prax's ex-wife and Mei's mother to describe details of abuse.
Battle of Io
After she and Bobbie joins the crew of the Rocinante using the Razorback found aboard the Guanshiyin, Avarasala transmits a video press statement revealing that she would be traveling to the Jovian system with Captain Holden. In it, she also clears Prax's name and blames the media for reporting unverified facts made by his ex-wife, Nicola Mulko, with "psychological issues"
Prax is dropped off with Amos and Bobbie. Leaving Bobbie outside the station, Prax goes inside with Amos where they encounter Strickland who kills one of his co-conspirators and feigns noble intentions to protect Mei. Not deceived, Strickland is killed and Mei is extracted along with some of the other children.
Avasarala retains the crew of the Rocinante to transport her back to Luna where she invites them to an appreciation party in their honor. There, she hires Prax to help with the efforts to rebuild Ganymede.
The System War
A research colleague of his for the past two and a half years since reconstruction began, Karvonides, is murdered the night she tried to coax him to release the new Hy1810 yeast and to attend a meeting to understand why. He suspects the Free Navy but is unwilling to speak up for fear of reprisal.
During the War, Prax worked on and surreptitiously leaked research for the modified yeast which contained an artificial chloroplast that was reverse-engineered from the protomolecule to make energy from a wider range of radiation than natural flora. This action enables Earth to provide food to the devastated population. Free Navy agents detain and interrogate Prax over the leak but, without determining conclusive culpability, they release him with a warning in order to tend to a new priority.
- The young hacker that Prax engages to access surveillance video feeds of Ganymede is unnamed in Caliban's War; however, the television adaptation assigns the person the name of Roma (or Romo) in an episode titled "Cascade" in Season 2. This is revealed in the promo and sneak peek videos produced for the episode.
- "The Expanse: Caliban's War", Chapter 3
- "The Expanse: Caliban's War", Chapter 7
- "The Expanse: Caliban's War", Chapter 10
- "The Expanse: Caliban's War", Chapter 13
- "The Expanse: Caliban's War", Chapter 14
- "The Expanse: Caliban's War" Chapter 19
- "The Expanse: Caliban's War" Chapter 27
- "The Expanse: Caliban's War" Chapter 31
- "The Expanse: Caliban's War" Chapter 33
- "The Expanse: Caliban's War", Chapter 33 & 34
- "The Expanse: Caliban's War", Chapter 36
- "The Expanse: Caliban's War", Chapter 36
- "The Expanse: Caliban's War", Chapter 38
- "The Expanse: Caliban's War", Chapter 41
- "The Expanse: Caliban's War", Chapter 51
- "The Expanse: Caliban's War", Chapter 52
- "The Expanse: Caliban's War", Chapter 54
- "The Expanse: Babylon's Ashes", Chapter 13
- "The Expanse: Babylon's Ashes", Chapter 24
- "The Expanse: Babylon's Ashes", Chapter 29
- "The Expanse: Babylon's Ashes", Chapter 40