Did I say I wasn't gonna upload anything new for the rest of the day? Haha, oops. My hand slipped.
These are my human takes on MK and Temmie.
Human!MK has arms, but wears clothing that doesn't allow them to move very well and is so long he trips on it all the time. Not the most practical, but he's cold often I suppose. (I'm calling MK a He based on the Japanese translation of Undertale and his profile on the artbook.) His eyes are a bit swollen from landing on his face all the time, and just like canon MK he's an upbeat child who all but worships Undyne and tries to follow her everywhere.
Temmie is... Temmie. She just does her thing and mostly refuses to use correct English. Shoots memes at the rest of the underground at an impressive rate of TEM per minute. She's the young leader of the Tem Tribe (a counterculture group of hippie-like teens and young adults who live in their own little village in the underground and all look suspiciously similar to each other) and aspires to pursue higher education, but is also an irredeemable hoarder so she'll buy ANYTHING off people and lose all her savings. Finds puppies really darn cute, but she's allergic to them. Puppies also seem to be commonly allergic to her and some of her tribespeople.
Among her tribe, Bob is the only person with a degree but gave up the opportunity of a steady job to live with the tribe. Overall beloved among the Tems, but doesn't quite blend in. (Might include Bob in some later stuff if I end up doing concept artwork of minor characters.)