Concept: Mix in cloning tank

The Xenos were the result of the Project Prime investigation, with time producing these critters became faster and easier in general compared to creation of machines that could perform similar tasks, so the Consortium decided to keep pushing the investigation.

Xenos aren't that many in general society, and most of them are more widely used in Consortium-specific installation, specially in the Consortium City (where the comic events takes place).

Despite this fact, in the Project Prime timelines there are many more Xenos and they're more common to find. Some species are more numerous  than others: Mice Xenos tend to be produced in large numbers compared to cats, dogs and even lizards.

The most common Xenos  are:

Beta 1 cats: remainings of the early experiments they can be found serving as assistants, secretaries, delivery, etc. Some scientists decided to take some of these basic Xenos from previous trials and keep them around the lab

Exigus mice: they're oftenly trained to keep maintenance to key equipment around labs, some of them even work on factories or military bases fixing up the gear.

Beta 1 and 2 dogs: these guys could be seen as assistants for the Survival function patrols, but they're more oftenly found guarding important buildings (from hospitals, to labs, even some factories)
Beta 2 and 3 cats: Despite they being the very first Xenos created, they're were not produced in big numbers, they are oftenly trained as infiltrators or assassins. Their use is more specific.

Lizards: these guys are rarely seen, they're not so many or so few, but they're often located in harsh or solitary environments, outside of the public eye.

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Sheep and other species: these guys are very rare, and still under development

Gamma dogs: these are rare too, since they're pets, expensive ones. They're usually made as gifts for important families.

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Xenos can only be produced by having these special tanks in special installations.
These creatures carry genetic markings that prevents them for being fertile by hormonal or lack of key hormonal cycles.

The idea behind this is to prevent reproduction and more mutation, most xenos of the same line of production are almost genetically identical (the procedure allows certain variation and sometimes the expression of non important genes likes fur color or having human-like hair)