So here is the story behind this image...
Cyrus, the cub by Mufasa, is Simba's younger brother, but yet stronger and as big as him, and with a bigger mane. He is Simba's half brother, in real prides, the male is the father of all cubs, so Cyrus is the son of Mufasa and Sarafina. Sarabi is fine with this because in order to make the pride stronger there has to be more offspring. Cyrus is around whe Simba leaves, and becomes friends with Nala and her friends.