A dragon has emerged out of a brook. — This is said when a great man emerged out of the most unlikely background. That is, what appears so unlikely happened strikingly in reality. It also suggests that a long river can be an analogy, embodiment, or at least the birthplace of a dragon.

The dragon has risen. — Idiom meaning that there is no water in this paddy.

It happened just as I thought it would.

Are dragons real?

He/she isn't marriage material, [I just meet him/her] for a casual relationship.