How good is he? Does he remotely keep up with you? Are you the one constantly winning or is he? If your styles are predictable, then that obviously needs to change in order for you to improve. There are good things to keep and bad things to get rid of when you're playing. Based on your selected characters below your avatar, you've got three characters who are good at spacing. At least that's how I would look at it. If you're using Sheik and you're always fairing your roommate, then yes, he'll expect it. Try a different approach. Do empty hops (which is just jumping around in front of your opponent without attack, but also being at a good distance from getting hit) and see how your roommate reacts. Does he shield? Does he dodge? Roll? Whatever he does, abuse it. So if he blocks as you empty hop, then go for a grab. If he likes to dodge on the ground a lot, then perhaps it would be best to delay your attacks or simply hold the smash attack a tad longer so that he'll get hit.
If you're not recognizing that you're being predictable, then you're playing in a mindset where you're just randomly throwing out things and hoping it'll work, or you're acting in a sequence. It's referred to as "auto-piloting". You're not actually focusing on what your opponent is doing. At least he's not. If you're predictable to him and he's predictable to you, then you've both become conditioned to the point that if you do try something new, you or he may not expect it.
I started playing Smash 4 a year and some months before my brother did and with him playing me a lot and me telling him what he's doing wrong and doing right, as well as he practice in For Glory or in Anther's Ladder, he's gotten better. Tonight, he effed me up to the point I blew my lid. I got so salty. But I shouldn't have, because that's good he's getting better or at my level. If you and your roommate are consistent in practicing, you'll notice a difference. My brother didn't think he was getting good, but I was seeing it and I wasn't saying that he was just to make him feel better. Challenge each other. Give input to one another. Don't take it as negative criticism, because when you do or if your roommate does, then neither of you will improve faster than you could. If you can go to tourneys, attend them. No point falling behind with someone who won't give you the time of day.