quot;Social contract theory from Hobbes to John Rawls suggests that the institution of contract may have value as practice and metaphor precisely

"Social contract theory from Hobbes to John Rawls suggests that 

the institution of contract may have value as practice and metaphor precisely because it is a model of cooperation that is consistent with personal enmity."

What does it mean? Does that mean the contract build with people's willingness or a contract can happen between two people hate each other.