果然 / 果真【guǒrán / guǒzhēn】

果然 means "sure enough, just as expected". Something was said, predicted or suspected first, and 果然 confirms it came true. It goes after the subject, or at the start of the clause.

The expectation doesn't have to be spoken. A reputation or a hint is enough.

果然 or 竟然

果然 is for an outcome that matches what you expected. 竟然 is for one that surprises you. A minimal pair:

• × 我以为他会赢，他果然输了 → 我以为他会赢，他竟然输了

果真

果真 means the same, and is a little more written. It also works in a condition, "if it's really true that…".