What does "Schlängelgang" mean? I wasn't able to find it anywhere. This is from Fontane's Stine:
Ich verstehe mich ein bißchen auf das menschliche Herz; denn sieh, wer jahrelang auf dem Krankenbett liegt, der hat viel Zeit und spürt vielem nach, und das Verlockendste sind immer die Schlängelgänge des Herzens, des eignen und des der andern.
It means walking in meandering lines. Schlängelgang comes from geschlängelt (meandering, snake-like), which comes from Schlange (snake), referencing the sinuous way snakes move.
das Verlockendste sind immer die Schlängelgänge des Herzens
You could roughly translate this as
the most tempting are always the meandering walks of the heart
or, as Takkat suggested, more poetically,
the winding trails of the heart.
From few references available there may be two meanings than can either be a movement in a winding or snake like fashion, or it can have the meaning of a path that meanders like a labyrinth. For both meanings usage is rare.
As for a translation of Fontane's poetic usage let me suggest a similar proverb like:
[wound] trails of the heart
