原来 (so it turns out / all along)

"Oh — so that's it!"

• original原来yuán lái marks a sudden realisation: something was true all along.
• original原来yuán láito be / is是shìyou你nǐ！ = "oh, it's you!" (I didn't realise before).
• It reveals a fact you've only just understood.

Subj + original原来yuán lái + Predicate

• original原来yuán lái = "so it turns out / all along".

so it turns out原来yuán láiyou你nǐare在zàihere这儿zhèr。

• original原来yuán láiyou你nǐat / in在zàihere这儿zhè ér = "so this is where you've been!"

A discovery, looking back

• original原来yuán lái reframes what you now realise was already the case.

Recap

Read the full reference: HSK 4 grammar — Adverbs.