What relation are Sue and Johnny in "Fantastic Four"?

Sue and Johnny in Fantastic Four are brother and sister.

Sue Storm and Johnny Storm are siblings in Marvel’s Fantastic Four. Sue is the older sister, while Johnny is her younger brother. They gained their powers after being exposed to cosmic radiation during a space mission with Reed Richards and Ben Grimm, forming the superhero team known as the Fantastic Four.

Sue became the Invisible Girl, later commonly called the Invisible Woman, and can create force fields and bend light to become invisible. Johnny became the Human Torch, whose powers include flight, fire generation and the ability to raise his body temperature dramatically.

Their relationship is central to the team’s personality. Sue often acts as Johnny’s protector and moral counterweight, while Johnny’s impulsiveness and showmanship frequently create tension. Despite their arguments, the two have a strong family bond and repeatedly fight together against threats such as Doctor Doom and Galactus.

A common mix-up comes from Sue’s marriage to Reed Richards, who is Johnny’s brother-in-law, not his biological brother.