...here are some more characters who play major roles in Chliever and Winston's stories:

The Floating Hyacinth: Chliever and Winston's Head of Department, so of course he shows up occasionally. At one point, he sends them on a punishment mission to the entire works of Starjeffry.

Agent Grendel de Bry: The self-proclaimed "Morally-ambiguous head of genetics and regeneration" for the Medical Department. He's responsible for all tanks in HQ, such as the regeneration tanks and the Floating Hyacinth's tank. He enjoys randomly breaking into bouts of evil laughter, wearing horrible-smelling latex gloves, and generally looking and acting a lot like Professor Hojo.

The Insane Canon: This (canonically) insane canon character is saved from a squickfic by Chliever and Winston, is sent to Medical for treatment, and subsequently escapes, ultimately moving in with Chliever and Winston despite their protests. Who this is is a pretty big spoiler for the early missions, so I won't tell you just yet, but I am well-versed in this person's native canon and thus should be able to write them fairly well.

Chliever's Dumbass Brothers-in-law: Algort the Contaminator, Pustol the Mortifier, and Burt the Stealer of One Sock from Each Pair respectively. These three get dumped by the Warp into the RC and immediately make with the mooching. They'll appear from mission three onward.

Chliever's Nerglings: Chliever has thirteen adorable Nerglings back home. Most of his paycheck gets sent to them. They may move into the RC later on, I'm not sure yet.

Agent Michel Javert: If Tomato will let me use him, I've got a big role planned for him later on.

EPC: Yep, I'm planning to do a Mirror Multiverse story. Features appearances by the mirror Dr. Fitzgerald and Bashir Hologram, the latter of who's identity is... disturbing, to say the least.