What is the most important skill the customer care or retention employee should be?

I think1 skill MUST be founded (( Communications )) he / she must have the art of listne more talk in order to know well the need of the customer before even he / she ask for it.

Overall Communication skills which includes Listening, Speaking as well as Non-verbal skills.

Being a good listeBeing a good listener  

By years of experience people need someone who listen to them and many of customers issues will be resolved by listening and giving attention

I think patience , multitasking , working under pressure and an open mind

Giving other person the confidence that you are there for him and her. Only then he/she would have confidence to come to you and hav etrust that his/her issue would be resolved.