You end up with someone on your team
who rushes to be first done- no matter how well done,
who constantly questions what you are doing,
who does not know how to compliment a fellow worker
causing that worker to feel that they are not good at the job.
Several thing you can do:
casually mention the problems.
be focused and simply get the work done.
pull the person aside and work though to solutions.
and if all else fails
give less hours.