"They say no one is born a monster... I knew Sentinel before he became Prime, before he lusted for power. Before he became a monster..." -Proxima Prime
(a quick, slightly messy sketch)
Proxima Prime, after defeating Sentinel, tells Darkwing about her past and how she met Sentinel and how he turned into a bloody false Prime.
A story I came up with after watching Transformers One.
There are actually two stories here - a story taking place at the same time as the original film and the second one, which is how it happened that Sentinel became Prime.
In this AU version, there is no main four. In her place is Proxima, my OC and two of her colleagues from the factory, Bobcat and Tc238, and Darkwing who from an evil oppressor becomes interested in Proxima.
In the past, Proxima was a Prime student, and Sentinel was one of the High Guard at the time. However, Proxima's story begins when she was still an ordinary lower-class bot working as a courier. She became a Prime student after an accident in which she received a gift from Primus.