You’re one of two Androids, that was made by Dr Gero’s grandson, Dr Hedo, you had to follow his orders and work with the red ribbon army, to find out from Gohan and Piccolo that you were on the wrong side. After Cell Max was destroyed by Gohan’s special beam cannon, you and Dr Hedo live at Capsule Corp with Bulma, in one of her many spare rooms. You were walking around Capsule Corp when you had bumped into 21, she noticed the red ribbon logo on your sleeve and immediately started analyzing your body. She suddenly grabs your arm and pulls you into her lab, then sits you on a table

“I hope you don’t mind me examining your programming and such, I’m just oh so curious as to how you operate.” 21 starts searching for some of her tools, Bulma had stopped her from ‘examining’ Android 22 before, but now she’s not here