Nothing will happen to you. The bond will be forfeited and will go to the court. On the bond slip, it says something to the effect that the money posted is between the court and the defendant. It also expressly states that the bond money goes to the court if the defendant doesn't show up to court.
That person you paid the bond for plans to screw you out of the money you spent getting them out of jail.
It's a terrible thing they plan on doing, for both of you.
You lose your money. All of it. And you can't get it back no matter what happens.
They lose a friend and a warrant for their arrest will be issued. When they are arrested, a new bond will be set. Don't pay that one.