Nega-Sean is Sean's polar opposite in Sonic's Reality Check, appearing first (chronologically) in either Chapter 7 or 8, whenever he was impersonating Shadow to mess up his relationship with Rouge. This wasn't revealed until Chapter 14 of SRC, when he abandons his disguise inside the Mii Plaza.
Nega-Sean is cunning and dangerous, which is much like his counterpart Sean. However, due to Sean doing evil things most of the time (although not evil for the protagonists), Nega-Sean ends up doing helpful things most of time, which is irritating to all but him, since he doesn't realize it.
Nega-Sean hates Godzilla and Castlevania, and he prefers other old games like Megaman over them. Nega-Sean also has shown disgust over impersonating his positive twin, as seen when he tried to steal back the Chaos Emerald from the protagonists in one of SRC's more recent chapters.
Nega-Sean also has proven to be quite irritating at times, although not too often, providing a stark contrast to the constant times Sean bugs the Sonic cast.
Nega-Sean, unlike Nega-Nick, still retains his basic clothing articles from his first conception outside the Mii Plaza. (That is to say, he still looks exactly like Sean).
Relations With Other Characters
- Sonic The Hedgehog (Human)
- Miles "Tails" Prower (Human)
- Knuckles The Echinda (Human)
- Amy Rose (Human)
- Jet The Bird (Human)
- Shadow The Hedgehog (Human)
- Rouge The Bat (Human)
- Sean (arch enemy)
- Matt (Sonic's Reality Check)
- Nick's Family
- Nega-Sean worked alongside Neil and Justin in the same chapter where he was assigned to steal back the Chaos Emerald from the heroes, although it should be noted that (like Sean) he tagged along to "bug" Neil and Justin.
- Nega-Sean was beaten by Nick before he could get the Emerald, because he wasn't informed of Sean leaving SRC for a week to go to Godzilla-con.
- Nega-Sean has shown the second most disdain at being a counterpart of his opposite. The first is Nega-Nick.
- Nega-Sean was the first of the villains to notice the Seedrians.