Dusty is an invincible companion that will follow you everywhere you go and kill early enemies like scavengers, wolfes and blood flies for you.

1. Talk to Dusty in the old camp, he will tell you about Melvin
2. Go to the brotherhood and talk to Melvin (he will tell you that he likes the brotherhood way better and that Dusty should come)
3. Go to the old camp and tell Dusty
4. Leave the old camp through the back entrance either draw your weapon while leaving so the dialogue does not trigger or pay the guards off

You now have an invincible companion that you can take with you to clean out most of the forest and get a lot of XP. You can't take him with you into mines and some strong enemies will cause him to panic and run. If he runs he will return to the old camp where you can pick him up again. And of course if you go with him to the swamp camp he will be gone forever. If Dusty gets stuck on trees while fighting, hit the animal that is stuck with him and he should get unstuck again.

Please let me know what adventures you have with Dusty. I really struggled to use him against any stronger enemies because his damage is very basic.