Any team with a goal as complex as saving humanity and fighting to overcome overwhelming odds needs a good psychopath. That one person that is willing to go that extra mile to make sure the job gets done, that petty morals won't get in the way of their objective. Mass Effect 2 has such a character, and while usually I'd be very eager to recruit such a person, the Krogan and Garrus took priority over him.
 
But with the two out of the way, the urge to talk and meet the game's mentally disturbed became irresistible. Ignoring the constant message that told me I needed a scientist to access the Normandy's lab and install weapon upgrades, I decided to head towards the Purgatory to recruit the feared criminal, Subject Zero.

Arriving at the space-prison, BioWare depicted the installation as a high-security prison for the most dangerous criminals in the galaxy. The way the facility is run is pretty unsavory, with planets paying monthly fees to keep the criminals secured, and when they don't, the Purgatory can choose to release the prisoners back on those planets, at an unspecified time and place. So, while guards abuse their power inside the Purgatory, like in any other prison, inmates rarely die, since, as long as they're alive, they're a constant source of income.

Refusing to relinquish my weapons, like any good Renegade, the warden eventually allowed me to enter fully equipped to collect Subject Zero, but had a change of heart half way through. The warden decided that Shepard was more valuable as a prisoner aboard the Purgatory than as a buyer for Zero, so I found myself assaulted by the prison guards. This is probably one of the many moments in the game where being a Renegade really helps. I don't know what would have happened if I had turned over my weapons when I was asked to.

The fights here are pretty easy at the beginning, though you get an assortment of enemies. There are mercenaries, Krogans and even FENRIS mechs, but, even so, it's pretty easy. Pushing through them, you finally find Zero's prison "cell," a cryogenic tank, and since this was your original purpose, you release him. The ruthless criminal turns out to be a woman, and a biotic with devastating abilities. While security protocols are engaged, and we chase after her, the destruction she leaves behind her is more than impressive. The hulls of YMIR mechs are left scattered about, torn open like tin cans and a full-blown riot kicks in in the Purgatory.

The final boss fight with the warden could be really difficult, but his weak point is a little bit too obvious. Surrounded by a huge shield, the three batteries that support it are very easy to distinguish from the rest of the environment, so while you send your team to engage all the mercenaries present, you can take your time and destroy the batteries. Snipping them is the easiest way to do it, with minimum logistics on your part, but I preferred saving my ammo for the warden and I closed in on all three batteries. From here on out it was a fair fight, and with Garrus and Grunt on my side, things went down very smoothly.

Catching up to my prey, running through the burning inferno that the Purgatory has become, you catch a few more cinematic glimpses of her tearing apart a few guards. As for the actual recruitment, things go a little bit too smoothly. For someone that kills everyone in sight, she's rather eager to join my team. Even if, truth be told, I'm her only way out of the burning ship.
 
The only thing Jack (that's her real name, and if she doesn't remind you of Kira and Crematoria from the Chronicles of Riddick, then you just weren't paying enough attention to either the game or the movie) wants is access to the Cerberus database, which I bluffed about and said I would allow her. The thing is, I really wanted a psychopath on my team, so I ended up keeping my word. Now let's just hope she lives up to her murderous reputation.