Hm... I'm going to split the topic before I answer, because I can think of several characters whose players might provide good answers to that question, myself included, and I don't wanna jack Naup's thread.
Done.
For me, the choice to play an outright villain stemmed from my love of the Minmatar Tribes and their underdog position among the 4 Empires. When I was starting to get into the RP scene finally, I'd already been doing solo and small gang (what would now be called micro-gang) piracy in the traditional sense (hunt, catch, ransom, destroy only if ransom declined). At that time, there were several minmatar RP corps, but almost all of them were in one of two alliances: Electus Matari or Ushra'khan. Ushra'khan's corps that were recruiting, I seem to recall, wanted 10m SP or more. I was at like 6-7m. And of course, Electus Matari required that you follow their NRDS RoE (which, as a young and eager mystified by the gloried and storied antics of pirate bloggers like
flashfresh and
Kane Rizzel and every contributor at
http://eve-pirate.com, NRDS just wasn't going to work for me).
So here I was, Minmatar pvper wanting to RP, not a fan of Gallente lore, Caldari seemed okay but were allied with Amarr, and there was Amarr... I could've gone for one of the Pirate factions, and I thought about it, but most of those active corps that pvp'd (not like there were many to begin with) had the SP requirement thing going on as well. Nature of the game. So I decided to do something a little different. Minmatar Tribal Terrorist. There was support for it in PF with the Defiants and I think a group called Bloody Hand of Matar (or something similar?).
So I thought about
how to do that. One of the things I hated about the Amarr RP players back then (still do) was how many of them seemed to cleave to a belief in their characters as 'the good guy'.
John Q Amarrian > /emote waves dismissive hand at slave #94 after having slave #28 taste for poison. "You may go."
See, I didn't beat my slave, my character is a good person doing God's Great Work hurrdurr.
I'm like, "No, your character's a fucking slaver, I don't care if he cures cancer, he's a bloody villain." Minmatar and Amarr are unique in Eve, in my opinion, as they are the only clear-cut 'good' and 'bad' factions taken
at face value. Obviously, the Minmatar aren't 'all good', and it doesn't take much digging through the PF to find evidence of this. And I'm certainly not saying the Amarr are 'all bad' - there's plenty of room for Oskar Schindler in the Empire.
Then I considered the essense of what a
terrorist is. DMX has a line in one of his songs, "There's a difference between doing wrong and being wrong." Those are the words Havo more or less lived by. He's mad, I've drawn from lots of inspirational sources from comic book villains, movie villains, even a soap opera anti-hero. The objective was to play a character who adamantly believed that he was good, that he was
right, that he was doing the
right thing, making the 'hard choices' that others were afraid or unwilling to make, breaking the eggs to make the omelette while your Electus Mataris and Ushra'khans would let the People starve. Who knew and understood that the actions themselves were terrible, that he would be universally hated for them, but who believed that strongly in their necessity.
Another facet of the contemporary terrorist is that they seek to attract as much attention as possible by attempting to outdo the last major terror attack if at all possible. And then they claim responsibility and use the moment of international notoriety to push a bit of their propaganda and attempt to attract followers/supporters/recruits. At that point, it was pretty much decided for me that Havohej couldn't be any sort of moderate. He had to be the extremist, there could be no compromising his views, no wavering from the "Let My People Go" agenda. I was going to play a Chaotic Evil against the Lawful Evil of the Amarr Empire and the Neutral Good of the Minmatar Republic, and I was going to attract as much attention as possible while doing so.
As I mentioned to begin with, I think that every player whose fashioned an outright villain of their character would have an entirely different answer, but there it was for me. TL;DR - I wanted to do something none of the other Minmatar were doing at the time and play the Minmatar bad guy.