Board Thread:Off Topic/@comment-25396609-20160125214134/@comment-25396609-20170401051224

even if it wasn't a mutual agreement, it did use another grimm to its advantage; the idea behind listing how they interact is that some grimm, for example two fairly intelligent but distinct species, might find it advantageous to work together; or a smarter one will use a dumber one to its own advantage.

but to kill eachother outright, or to fight other grimm, is against their nature; actively harming eachother would only make it harder to wipe out humanity.