This is a embellishment that was on Cloud Strife's shoulder plate in the Final Fantasy VII movie:Advent Children. It is a representation of the Fenris(or Fenrir) Wolf of Norse Mythology, which Final Fantasy VII relied along strongly in in story(Midgard, Nibelheim)
Its a symbol of Fenrir and his ties to the ancient summon, symbolising him as a 'lonewolf' someone who searches for answers, likes to be alone, to be forgiven :)