Been using the username for years. It was originally Speratus, a name of a red mage in the Dragonlance universe I found. As it turns out, he eventually gets eaten by a dragon who impersonates him. I can't really find the place I found it anymore, but if memory serves, that is correct. The 3 came not long after, because it looked "cool" to have some leet-speak in the username, but it has stuck since, which is a pretty good thing, as it makes me able to identify whether it's me or not. Apparently there's a guy way back, who's called Paul Speratus.
As for the avatar, it's one of the panels from the Concerned Half-life comic that ran a couple of years back(it's still up, in case you're interested), where the protagonist Frohman hangs up motivational posters, this being one of them. I'm pretty sure you can guess where the idea for the poster comes from.