Sorrana has two very distinct fighting styles - Helis and Lunis. Swapping between both of these near polar opposites leads to a very jarring encounter, they're never going to know what comes next.
During Helis, you should roleplay Sorrana as almost rabid. She is hungry to lay waste to the foes before her. She will become hyper aggressive, and will take risks that may leave her in a bad spot to land a devastating blow against a key opponent. Utilize her more aggressive toolkit in Spinning Slash and Vicious Strikes to dish out tons of damage. There is no limit on the amount of times an opponent can be hit by the fire damage of Spinning Slash.
During Lunis, she is calm, collected, and reserved. Describe her taking on a more defensive front, eliminating most of, if not all of her openings. She will move intelligently, and leave herself well positioned to deal with whatever the enemy is throwing at her. Utilize her more defensive toolkit between Fanatical Shield and Chilling Strike to control the battlefield a little more.
Sorrana is generally extremely pleasant. If she spies someone in need, no matter how little the issue, she'll help out. In roleplay, you should play her as such, but sprinkle in some notes that she has definitely seen some stuff in her lifetime. In a roleplay situation, the second she feels threatened, or feels as though the person she's speaking to is withholding information, her personality will change to be that of the more aggressive Helis. She will remain this way until the event that caused her to go there resolved or if combat begins.
During Helis, she is short tempered, bad mannered, and will be hyper aggressive towards everyone she views as a threat. She does not prefer this side of things, but recognizes that it has its place. "All good blades have two edges", she is often heard saying.
Since then, that has been her only goal.