github encourages 1 fork per user, so that that user can work independently on a feature and then request that feature to be accepted into the main repository via pull request.

However, what if 2 developers need to collaborate on that feature? What is the ideal workflow for this? I could see a number of options:

1. Both developers fork the original repository. Each developer pulls/pushes changes between each other's repository. This seems like a lot of work (tiny micro operations) and also creates a delay between changes, so increases the window for conflicts.
2. Developer 1 forks from the main repository, developer 2 forks from developer 1. Same as #1 mainly but hopefully simplifies Developer 2's life a little?
3. Developer 1 gives Developer 2 permissions to his own fork, so they both work out of the same central repository. Not sure if this is ideal.

I'm also curious where branches come into this. Obviously there would be a branch for the feature itself but that branch can't exist in a single place, it would have to exist on multiple forks and be synchronized.

Basically just really confused about this workflow, would like an approach for how this can be best accomplished.