I must have missed some things along the way. I know he was beginning to chafe, but what exactly did Ted do to create this situation? Comes off like a complete villain.
Happy for Danny Rojas. The greyhound puppy was genius. 
Did you notice the puppy was wearing a helmet? I missed that the first time around. The story-telling is just incredible on this show.
Pretty much everyone, including Ted, dismissed Nate as a serious person on the same level as Ted, Beard, and Roy. Ted would use his ideas, but there were a lot of instances in which Ted dismissed him. Plus Nate has some serious Daddy issues so he probably takes it out on Ted because he won't stand up to his own father.
Nick Mohammed (who plays Nate) provided some context:
https://pbs.twimg.com/media/FBL-8LpVEAkSZvH?format=png&name=medium
