This is how Thunderwing corrupts Princess Cadance goes in
Thunderwing: Seems I haven't given you enough information about my evil plan. You see, not only do I want to make more Dark Energon, but I want to use it to make you my Dark Princess.
Princess Cadance: Dark Princess? You planned this?
Thunderwing: Yes, Princess Cadance. Soon you will succumb to my master's lifeblood.
Princess Cadance: What are you going to do to me?
Thunderwing: You'll see.