How this would be done would be simple.
The surgery table.
In labs/possibly on station, there will be a surgery machine to add organs to yourself.
Cat ears may or may not be provided by the facilities. Whatever you do, do not add them to yourself unless you want to permanently have cat ears on. Prosthetic organs can be added to yourself to increase your physical defense at the cost of your arcane (as well as a need to weld instead of bandage).
Stranger organs can be harvested from the depths, which can provide benefits at the cost of reducing overall humanity, along with the usual costs of said organs.
For example, Colossus organs provide the user with information and holiness at the cost of their sanity, as well as information overload. If someone were to be mad enough to graft all the senses of the Colossus into themself, they might become something a lot holier, at the cost of having to filter out excess information/being weak to going insane.
Implanting the organs of an angel into yourself sounds badass, but what would each boss organ do?
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