"Greetings. I am Edwin Odesseiron. You simians may merely refer to me as 'Sir,' if you prefer a less... syllable-intensive workout."
Even when in the middle of a conversation, Edwin takes time out to tell himself something or to insult the people he's talking to (As if they couldn't hear him). He's a Red Wizard, a member of a powerful cult of Wizards that rule the land of Thay. Most everyone in this organization are black hearted power mongers, and Edwin is no exception. He is also tattooed in the manner of the Red Wizards and has a Slavic accent. Despite the notorious reputation of that group, he wears Red Wizard robes proudly.
He has several goals which he believes will give him exceeding amounts of power; typically, these plots go over very poorly for him. When, for example, he gets his hands on 'The Nether Scroll', he does undergo a remarkable transformation, but its effects are far from turning him into the almighty being he imagined. Getting the scrolls for him and fixing how badly he botches using them are quests in themselves.
In Baldur's Gate Edwin is out to murder his rival, a Witch named Dynaheir, and if you encounter him before you meet her, he will try to hire you to kill her for him. If he is in your party when she is found, he will go hostile if you refuse to kill her, but if you recruit her separately and then talk to him, he will want to join your group in order to keep an eye on her. He'll exclaim in joy 'Checkmate!' if she dies.
In Baldur's Gate II he can be found working for the Shadow Thieves, but his agenda is still very much his own, and he is busily hunting for the previously mentioned Nether Scroll - it is later revealed that he is on the run from Thay for not fulfilling his obligations to the Red Wizards. Although many people rise up to fill mantles of great destiny around him, he remains the same power hungry wizard as he always was. This greatly upsets him in some of the inter-character conversations. He despises those he regards as inferior to him (which is everybody) and is deeply envious of those who clearly are not - he makes a number of references to Elminster and how he is going to beat him one day, and clearly hates the better known wizard.
Finally, he's hilarious. He never intentionally tries to be so - he considers himself deadly serious at all times - but the things he says things to himself and in the way he consistently fails just before his all be assured accent into the halls of power provide a welcome element of comedy into the game. His epilogue at the end of BG II:Throne of Bhaal is a highlight in this regard.
Edwin is voiced by Jim Meskimen.