Hardened wire is difficult to "use in a perpendicular" way. It really isn't meant to bend, or twist. It is a flowing substance, like for bicycle cables!
Guitar strings, you can just buy a set of new ones for a few dollars.
To fuse the ends is relatively easy. If you have a Propane Torch, check to see if it is MAPP gas compatible. If you don't know, just got to the Hardware or Lumber Center & ask for a MAPP torch, and maybe an extra "yellow" can of MAPP gas. Also ask for pre-fluxed brazing rods. You are almost going to weld, more molecular transfer of one metal to another. That is what brazing is. You get the ends positioned so they don't move. A couple 7" or larger vice Grips should work. Put the vice grips both parallel to the surface you are using for brazing. An old lawnmower blade will work. NOT concrete, plastic, wood, or any thing that will catch on fire. Steel or Iron.
You should have "Brazing Safety Glasses" They are specially tinted, no don't use sun glasses. ... flat surface.
Position the grips ~2" from the end of the wire, they will still get dangerously HOT. On the parallel part of the blade. Now the fun. Start the MAPP torch, centered, on the center of the 2 wires. Back to the torch, it should make the 2 ends "RED HOT" relatively quick, depending on their diameter. Red, not sparking... sparking means you are trying to weld. That is another day. The flux covered rod, goes right on the red hot parts of the wire. There is that microscopic bond. You can take a regular bastard file (yes that is the name of a file) and smooth off any large protuberances!
My next question is do you want to bend them to a shape, that stays, or are you doing 2d-3d stuff that the "circle has to go back flat" ? If that is so, you will just have to make the shape, and get the number of hands needed to hold it. If you want it static in shape. Mark the bend points with a marker. Get that very nice MAPP torch, keep it back a couple inches (not welding, or brazing) as it starts to get red bend it, let it cool and it will stay that shape. You've taken the temper out of the steel, by relaxing the crystalline structure of the steel. It will not spring back! Do the same for other bend spots.