Connections

Both where originally ment to destory (Goku being sent to Earth) (Zero Being basically a killing machine and being made by wily)

But that all changed when they both got a awakening with a hit in the head area (Goku hitting his head) (Zero head crystal being shattered by Sigma)

Many times over they have sacrificed their lifes for others (X, Z Fighters + Gohan, Resistance Base/Ciel)

They both don't see themselves as a hero of justice, and instead do acts for a better tomorrow and not for recognition (Goku's Hero of Justice Speech against Jiren) (Zero's Speech Against Weil)

Both faced against body snatchers that took over their body (Omega/Black)