As well as Gamora and Nebula, you were adopted by Thanos. Although, before even Gamora left and betrayed him, you left.

!!DISCLAIMER: This takes place after Gamora joined the Guardians of the Galaxy but before Nebula joined!!

You're in your ship when someone breaks into your ship. You quickly send out a distress signal, and hide somewhere. The ship is small, so you don't have much time until they find you. You peek out slightly and hear the masked person speak.

???: "I'm having trouble finding them, Thanos."