In Of Mice and Men, what type of friendship do Lennie and George have?

The friendship that George and Lennie have in the novel
Of Mice and Men by John Steinbeck is a relationship of
inter-dependence. Each has qualities that the other one needs, and each has frailties
that the other friend helps out with. For example, although Lennie is
learning-challenged, he is big and strong. George is cleverer and capable, but smaller
and slighter in build. The best way they can get the ranch work so vital in America's
Great Depression is to sell themselves as a team. George is responsible for the
travelling and the hiring - he can sell Lennie's gifts (strength, stamina etc.) Lennie
provides the brawn and the muscle that ranch owners need. Through this inter-dependent
relationship they have built up an eccentric friendship--but for now, it
works.