The one thing you probably haven't been doing is having friendly work-oriented talks with your boss. A couple of times a week you should have been raising some easy issue just as a "heads-up" so the boss is up to date.
The idea is to break down the social barrier between you two and make sure he knows you, feels relaxed around you, and knows you're competent. A related important goal is to make sure the boss knows that you two can work together as near-equals as part of a team. That's what being promoted really means, from the boss's point of view.
You've run into a colleague more of a predator than an engineer. I've also been pushed out this way and was foolishly resting on my technical laurels.
The idea is to break down the social barrier between you two and make sure he knows you, feels relaxed around you, and knows you're competent. A related important goal is to make sure the boss knows that you two can work together as near-equals as part of a team. That's what being promoted really means, from the boss's point of view.
You've run into a colleague more of a predator than an engineer. I've also been pushed out this way and was foolishly resting on my technical laurels.