Strangely, I rarely have the inclination to change my avatar on this forum. It doesn't seem worth it to throw people off, and I think I hit it nicely with Ciel. I am on my third avatar, I suppose...changed to Assassin for Halloween, and to Ilya for the winter. I think I might stick with an Ilya avatar when winter ends, though...
Strangest reason I'd ever changed my avatar? On the City of Heroes boards, when tensions were running high before the changeup between Issues 11 and 12, I finally got sick of all the flames and arguments, so I changed my avatar to Colette Brunel (it was her or Tohru Honda) and started deliberately acting as friendly, conciliatory, and non-snarky as I could. It was probably a futile gesture in the big picture, but I like to think it helped in a small way occasionally.