Loyalty
Definition:
the quality or state of being true and constant in support of someone, commitments, obligations or something.
Someone who is loyal is reliable and always true, like your trusty dog. Loyal comes from the Old French word loial which means something like "legal," but if someone is only loyal to you because the law requires him to be, that's not true loyalty, which should come from the heart, not a contract.
A truly loyal person is always sincere. They show very subtle, yet powerful signs that they care. You'll find that they are faithful in a way that they show up during the good times and the bad times. Loyal people are supportive (even loving) for no other reason than that they care.
Synonyms:
adhesion, allegiance, attachment, commitment, constancy, dedication, devotedness, devotion, faith, faithfulness, fastness, fealty, fidelity, piety, steadfastness