request Need help for Web Comic ideas and characters

[Marathon 562]

So I'm planning on doing an mlp Web comic (that I'll hopefully be able to post on here) and I have my general idea of what it will be about, but having difficulty expanding on it. So here is the general idea: There's a unicorn who developed a rare cancer only unicorns could get. It slowly over time increases their magic output to something that could rival an Alcorn's own magic but is also slowly killing them at the same time. A few unicorns who were plotting to over throw the princesses hear about this and are trying to capture this unicorn to steal his power.

 

In no way am I trying to make fun of people who do have cancer, but this is the basic idea. So anyone willing to help with some character development or story line is more than welcome to.