well, i am one of those subs who feel its always been in them, though with people i can overpower i get a bit Domme-ish.
as a little kid, only 8 or 9 years old, i would play dress up and pretend that i was kidnapped and sold into a brutal harem where i was beaten and raped repeatedly. . .yes at only 8. and nearly all of my games or physical activity involved me getting more than a little scraped and bruised. (this was all probably related to sexual abuse as a very young child)

in highschool i got myself into an abusive relationship that brought out the bad side of my submissive nature. it wasn't a D/s relationship, he stole control of every aspect of my life--it was never given. but i didn't care, he took away my identity and free will. i know i could have physically over powered him at that time, but i did nothing. i didn't even say "no" to anything (but i never said yes).

anyways. . .i eventually got out of that horrid situation. my current Dom started to bring out the good aspects of my submission, as i bring out the good of his dominance. we both seem to care more for the other's pleasure than our own, which is how i feel a true bdsm relationship should work (for us at least). unfortunately we stopped seeing each other for a few months mostly because he wasn't honest about his emotions, but gladly we're back together again and so far its much better now :-) i know that He could never actually harm me, and He knows that i will willingly do anything for Him.