Thread: What do you make of this behaviour

Bo is coming up 11 months now. He's a been a real joy to have as a pup and learns things pretty quick. He's and inside dog at night time and usually sleeps in the lounge with our other dog Knox, who is an 18yr old pureplbred Staffy. Both dogs are entire but pretty laid back sorts and have always got along well but lately they just seem "funny" around each other.
They have play heaps even though the old boy gets a bit sick of it sometimes and a short sharp snap tells Bo playtime is over. The other day however we were both in bed alseep when we were woken by them both going at it in the lounge having a massive (serious) scrap which they have never done before.
They have continued this "strange" behaviour since then and will sit on opposite sides of the room eyeballing each other.
Fast forward to this evening and I had just got out of the shower and was getting dressed when Bo came into the room, he came over and sat near me and Knox (older dog) came and sat in the doorway of the bedroom. Bo then proceeded to jump up onto the bed (which hes not allowed to do) and cocked his leg and pissed all over it right in front of me!
Is there some kind of power struggle going on here as Bo has reached the age where he thinks he can now be the top dog?