Ratthi

"This is why Ratthi is my friend." (Murderbot, Network Effect)

Overview
Ratthi appears in All Systems Red, Exit Strategy, Network Effect, "Home: Habitat, Range, Niche, Territory", and Fugitive Telemetry. He is mentioned in Artificial Condition and Rogue Protocol. He is tagged as "my human friend" by Murderbot.

Ratthi is the PreservationAux team biologist. He is not apparently married, though Murderbot observes that he “has an unrequited thing for Pin-Lee.” Later, in Network Effect, Murderbot noted that Ratthi “had a lot of relationships with all genders of humans and augmented humans and he and they all seemed very happy about it.”

In Network Effect, Ratthi is capable of rendering first-aid to Murderbot.

Ratthi does not live on Preservation Station, but occasionally stays in the hotel there.

Personality
Ratthi has a lively sense of humor and tends to be expressive. While Ratthi is initially the first human to try to get Murderbot to talk about its feelings (to Murderbot’s intense discomfort), he is later on one of the most accepting of Murderbot on its own terms. Murderbot notes that Ratthi listens to it carefully, and in return, Murderbot seems to be more comfortable with Ratthi than with anyone else other than Dr. Mensah.

Physical Appearance
There has been no canonical description of Ratthi in the texts, but Martha Wells has said extra-textually that Ratthi is incredibly attractive. It can be assumed through the text that Ratthi is shorter than Murderbot.

Murderbot ("SecUnit")
Ratthi is incredibly respectful of SecUnit's preferences and boundaries, which is why SecUnit regards Ratthi as its "human friend." When SecUnit needs help in Fugitive Telemetry, SecUnit calls for Ratthi's assistance (and assumes Ratthi won't ask questions). Ratth is also very defensive of his friend SecUnit and will not hesitate to speak up for it.