This is aggression, right? Please help!

[Navy]

My only issue is that MY training always gets counter-acted by hers. I taught him to sit and lay down; one day, my roommate asked him to do one of those and he rolled over. She was delighted and rewarded him whenever he did it, no matter what she asked him to do. Now ANY command of "sit", "down" or "stay" is "roll over". I could've pulled my hair out. He's NOT stupid, he's just getting rewarded for the WRONG thing, and now he thinks it's right.

I really think it's because he has NO experience with children, and not much with people in general either. I will try to start working with him, but unless I get my roommate's cooperation, she's just going to counter-act every training exercise I give him. He recognized me as "pack leader", but he won't listen to me a lick if she's anywhere within running distance since he knows she'll protect him. He'll go straight to her and then I get all barbs and sarcasm from her about "her" dog. I've tried to be nice and I've tried to be patient, but I don't think the dog's the real problem, I think it's the OWNER. Luckily our lease is up at the end of September and she will be moving elsewhere. I want to help her but how do you help someone who doesn't want to listen?! It's so frustrating!!!!

Yeah, she has no business owning a dog.
Dogs need training, proper training. Not just tricks but things like sit, stay, no.
Aggression should NEVER be tolerated. It's time for her to either taking him to a training specialist that will help him get past the aggression, or she has to get rid of the dog if it's your lease. Because if it is, if that dog bites someone, it comes back on your ass.
No matter if it's her dog or not, it's your responsibility.
Of course, this is only true if you're the lease owner.
Either way, she obviously shouldn't have that dog.