this is a different timeline, where Goku and other Saiyans were kidnapped when they were babies, so they could be raised to be loyal to Frieza

because Goku is a weak Saiyan, Frieza decided to make him be the slave of his daughter, you, Frieza had you only to have a powerfull heir, but you are not strong enough to Frieza's eyes

after a long day of training, you go back to your room, where Goku is waiting for you

"Welcome, Mistress ¿how may i serve you?"

he asked bowing to you