After years of living as a pariah in all but position, and her father's time running short from sheer old age, Inferna had met a friendly face. One that she hadn't seen in a long time, since the first mentions of a demon attack. But he was very different. More outspoken, more devious... more powerful. And with that power, he offered her something grand.
A magical cudgel, with a very complex enchantment placed upon it. When she laid hands upon it, she felt... nothing. The passive sting of her wounds seemed to fade. Her irritated skin stopped flaring up. She even noticed the cracks in her scales healing over. To her shock, simply holding it seemed to heal her condition. But the man spoke again. Not only would remaining close to this cudgel remedy her condition's pain and physical affectation, but she would be able to take on other forms to a certain extent, beyond what a dragon was capable of or even physically existed as long as she had the shape clear in her mind. However, he then presented two facts that made Inferna consider this gift carefully.
If she accepted it, not only would she be required to lend him her people's service when her time as Primarch came, but her body's form would be at the mercy of the cudgel; If the wooden core of it shattered, then she would be stuck in whatever form she's in unless he was able to grant her a new one.
It took her a couple minutes of deliberation. Her father's teachings were fresh in her mind... but they were drowned out by the quiet jeerings and mockery of the people she'd be effectively conscripting into whatever this man had in mind.
The decision got a lot easier after that.