Rainbow Dash made a promise that she'll protect everypony. Bound by the element of loyalty the effect of those words caused more to change in her then just a mindset. Now stuck in and endless cycle of death and rebirth she shares her story.
First IS story
Third IS story
This one has the gore tag because I didn't want to skimp on any details. (It's honestly not that bad though. Think early Mortal Kombat games.)