To call this horse 'a character' is a gross understatement 
Willie lets himself OUT and also IN to his stall - never mind latches and hooks. He unzips my coveralls, if there is nothing edible to be found in my pockets. He 'pouts' by flapping his bottom lip when I say 'No' 
He's certainly good for a laugh!
But, he's also very helpful. Bringing horses in at night has been a 3-minute deal all week. You really don't have to ask him twice. I call, I open his stall, and it's all 'Pardon me, coming through, MOVE!' after that. And then, he whinnies at Tika to get his behind inside. And it works!
I've seen the first 'spook' from him, now, too. Well... it was more of an exaggerated twitch, really; his feet never moved. Thank you, I can handle that. I hope it'll be the same under saddle.
He and Tika seem totally at ease with each other... in fact, I have not yet been able to determine who is alpha. Willie seems utterly confident and calm - something, I hope will rub off on Tika.