This must be an alternate Sonic whose MO is to make enemies keel over from his cuteness. He was doodled by kawacy, who otherwise specializes in anime-style art—his gallery is right here, if you want to check him out, and below’s a timelapse video depicting the painting process.

Here's an oil painting of Sora from the Kingdom Hearts series, based on this well-known piece of official concept art, done by artist Raman Singh. Look below for the HD pics, and check out Singh's portfolio for more, albeit non-gaming-themed, paintings in this style (I particularly like his portraits).