Based on the classical earthly-branch relations of your two zodiac animals — this combination may emphasize these tendencies; real people add the nuance.
Trine partners — same wavelength
Rat and Dragon belong to the same trine (San He) group — three branches that share one elemental current. They instinctively understand each other's pace and ambition, which makes them formidable allies in long projects and steady, loyal partners in love. Where six-harmony is chemistry, trine is shared worldview.
Expect mutual encouragement rather than sparks: this is the pairing that builds businesses and families side by side.