God again comes to Moses and Aaron, and says to Moses, "I have made you like God to Pharaoh, and your brother Aaron shall be your prophet" (7:1). He's not making Moses a god, but he is giving him divine powers.
God again promises to make Pharaoh stubborn so that the Egyptians can witness God's power. There's no show if he says go.
Aaron gets his turn using the magic snake-staff, but the Egyptian priests turn all of their staffs into snakes, too. Not to be outdone, Aaron's snake eats all the others. Grizzly.
God gives the pair the go-ahead, and Moses and Aaron use their power to turn the Nile's waters into blood. The fish all die and the Egyptians have to dig wells for water. Again, Pharaoh's priests replicate the miracle, and so Pharaoh goes back to his day job unimpressed by God's power.
Read Chapter 7 carefully, and you'll notice that it's kind of hard to tell at points whether Moses or Aaron is doing the magic. Here's an example:
Moses and Aaron did just as the Lord commanded. In the sight of Pharaoh and of his officials he lifted up the staff and struck the water in the river, and all the water in the river was turned into blood. (7.20)
If the story was originally just about Moses, somebody did a very good job of making sure that Aaron was as involved as possible in the new draft. Convenient for anyone claiming descent from Aaron, right?