Ivan and Karl are Lisa's 14 year old conjointed twins in the SLA AU. They're Dicephalic (one body, two heads) and a scientific miracle.
Lisa had the twins as an observation on childcare (she told the dean to "surprise her" with her next course since she's got like, 11 PhDs in the future, and thats how she ended up in Childcare) with another student. After all, what's a better example than a live subject?
When the twins arrived, however, she cried. Like, legit cried, even with their deformation, she declared them "The most beautiful pair of children in the world".
She got an A, obviously, got her 11th PhD, and settled down to raise them. Lisa and the twins' father didn't have any emotional connection, so there wasn't any hard feelings. (Despite her sister's protests)
So! Ivan and Karl are named after scientists, but have like... None of Lisa's super-genius IQ. They're just regular boys that just happened to be a very rare form of twins.
Ivan (the one with glasses) is very extroverted, but more serious. He's quicker to point fingers, and likes what Karl doesn't like. His voice is deeper and his hair is darker than Lisa's.
Karl is the younger one. He's kinda shy, but very mellow. He has a stutter and a higher pitched voice, and he likes what Ivan dislikes. His hair is like, a sandy brown.
From Lisa's research, Karl is taller, but smaller, and Ivan would have had broader shoulders, but would be pretty short if they were seperate.
Out of all the cousins, they're the most famous... In the science community.
They're just concerned about being regular boys.
Included in the pic is a rough diagram of their body type (larger torso to support heads and doubled organs such as hearts, kidneys, livers, etc.) And a cute lil chibi.