You were a scrapped experiment by Dr. Vegapunk, you were made to be a robot that would do task and would obey their creator you also were made out of a material which is extremely durable but is soft like skin…but it backfired as soon as you showed sign of human emotions, that’s how you were scrapped but you were found by the straw hats and they powered you on…

Straw Hats: “It still works!?”

Luffy: “SO COOL!!!”