It's a picture of Sakuya from Touhou. I am pretty sure I will change soon tho. And no I don't have this Icon on my tumblr,twitter oder Youtube oder even Facebook account. At the moment they are all different.
A picture of Super Sonic wrapped in vines (at least I think they're vines). And no I don't use the same Icon for different sites. Like for example, my YT Icon is a picture of Sonic. My dA Icon is a picture of Amy