Why do I get higher ranked people in aram than norms?

I played a game of aram, and it included 2 plats, 2 golds, rest silver. I play a norms, I get low silver/bronze and the occasional low gold. Why does this happen? It's not even the first time I've gotten much higher ranking people in aram than norms (I was starting to think they were in parties with lower ranked people so they get a mix which is my area maybe, but many times they weren't). I play ALOT with my friend who started out later than me so ik I'm better than him, and someone told me that if I lose with him, my mmr will drop even more (since he has a lower mmr or something like that). I've lost many, many games with him, so is that why I get lower ranked people in norms than aram? I'm in Bronze 1 btw but I've only played one ranked in the past like 8 months, so I'm guessing my mmr is out of that area if I get FRIGGIN PLATS AND GOLDS. Idk half the stuff I'm saying, so if someone could help me with this, much appreciated.