This is how Ryan find Princess Ivy and Ivy tells Ryan her story goes in season 3 of the episode Dreadlock in Ryan F-Freeman's Adventures of Transformers: Prime.
Ryan F-Freeman: I hope I can be a Prime and a prince someday.
[Crash nods and Ryan saw Black and white butterflies]
Ryan F-Freeman: Wow. Butterflies.
[Ryan follows then to the caverns of Cybertron