And now the house-dog stretched once more
  His limbs upon the glowing floor;
  The children half resume their play,
  Though from the warm hearth scared away;
  The good-wife left her spinning-wheel
  And spread with smiles the evening meal;
  The shepherd placed a seat and pressed
  To their poor fare the unknown guest,
  And he unclasped his mantle now,
  And raised the covering from his brow,
  Said, voyagers by land and sea
  Were seldom feasted daintily,
  And cheered his host by adding stern
  He’d no refinement to unlearn.

Which is what Heathcliff would have said sternly.  Observe the effect of him.

  A silence settled on the room,
  The cheerful welcome sank to gloom;
  But not those words, though cold or high,
  So froze their hospitable joy. 
  No—­there was something in his face,
  Some nameless thing which hid not grace,
  And something in his voice’s tone
  Which turned their blood as chill as stone. 
  The ringlets of his long black hair
  Fell o’er a cheek most ghastly fair. 
  Youthful he seemed—­but worn as they
  Who spend too soon their youthful day. 
  When his glance dropped, ’twas hard to quell
  Unbidden feelings’ hidden swell;
  And Pity scarce her tears could hide,
  So sweet that brow with all its pride. 
  But when upraised his eye would dart
  An icy shudder through the heart,
  Compassion changed to horror then,
  And fear to meet that gaze again.

  It was not hatred’s tiger-glare,
  Nor the wild anguish of despair;
  It was not either misery
  Which quickens friendship’s sympathy;
  No—­lightning all unearthly shone
  Deep in that dark eye’s circling zone,
  Such withering lightning as we deem
  None but a spirit’s look may beam;
  And glad were all when he turned away
  And wrapt him in his mantle grey,
  And hid his head upon his arm,
  And veiled from view his basilisk charm.

That, I take it, is Zamorna, that Byronic hero, again; but it is also uncommonly like Heathcliff, with “his basilisk eyes”.  And it is dated July 1839, seven years before Wuthering Heights was written.

The other crucial instance is a nameless poem to the Earth.

  I see around me piteous tombstones grey
  Stretching their shadows far away. 
  Beneath the turf my footsteps tread
  Lie low and lone the silent dead;
  Beneath the turf, beneath the mould,
  For ever dark, for ever cold. 
  And my eyes cannot hold the tears
  That memory hoards from vanished years. 
  For Time and Death and mortal pain
  Give wounds that will not heal again. 
  Let me remember half the woe
  I’ve seen and heard and felt below,
  And heaven itself, so pure and blest,
  Could never give my spirit rest. 
  Sweet land of light!  Thy children fair
  Know nought akin to our despair;