The two host-like guys are apparently already supposed to be EAT, but are guarding Anya. At least that's what it seemed like, but now Sid seems to imply the two are working for him as bait to lure out this iridescent hair threat.

Any advancement of these three would appear to be almost entirely on Tsugumi's shoulders. Learning to transform effectively and quickly, learning her special ability, etc. Anya is irrevocably attached to her, and Meme is probably too scatterbrained to remember anyone else aside from her roommates.