A person who does things for others may be an assistant or a helper.
you call it chemist i think
Gemologists
call someone
an industry
Taxonomy.
A critic
a troublemaker?
Someone that doesnt do things for others
Hypocritical
This would be an eavesdropper.
An altruist
Chauvinistic!
customer
Arch
Chemist
kind
a trapper hobble