Haunter is one of the five Pokemon in Death Reaper JOE's team, and comes from the Alternate Universe series. He is a relatively minor character, who only shows up when the situation of the comic calls for it. Unlike his brother, Gastly, Haunter likes to engage in Pokemon Battles. In fact, he likes to engage in anything where he can prove to be better than anyone else. Because he is both undead and powerful, Haunter is somewhat haughty and sure of himself, feeling that he can do and get away with anything. He will dare or even challenge anybody to best him at something.
Like his brother, Haunter likes to create mischief and goof off, and is also a sore loser just like Gastly. Unlike his brother, Haunter is loyal to Death Reaper JOE and welcomes a good scrap, as it gives him both something to do in his otherwise dull "life" of immortality, and more importantly, it will give him something that he can lord over his competition forever, should they lose. And make no mistake, he certainly has an eternity to do so.