Before I go on with my story, I might as well introduce my Ponysona properly.
This is Defenceless.

She was once tortured, kept as a pet by other ponies, yet with the help of her current husband, she found out her talent and was able to escape.
Changed this... to be a bit less torture. In fact, she was bullied in school, for being a fatty fat filly. One day, with encouragement of her childhood friend, now husband, she showed those bullies what it means to really be... well.. round. (Yes, I am liking this version much better already)
The name is from her being defenceless once, but now being the one in charge. And her cutiemark, a shattering shield, depicts that she likes to... expand things, to break through defences. Those bullies practically granted her her cutiemark.

After marrying her husband, she fell back into her desire, to fatten, feed, stuff or just generally expand other ponies, mostly out of curiousity to simply see reactions.
She is just fascinated by different situations and tries around, just what she can do. And perhaps she sometimes falls into the role being the one standing over others, instead of being the one who's tortured.
She also likes laying on soft things. Like bellys.

Her husband, a unicorn, helps her with most of the devices she needs for her 'hobby' yet, he doesn't know much about it. Nothing, to be exact. He only knows, that he has gained some pounds since their marriage.
She's going really slow on him...

I feel as if she isn't the best character, but I assume as time goes by, she will get better.