Characters
Here's a list of the characters that play major roles in GTA IV. Most of these characters give you missions at some point in the game and they will often call you wanting to socialize.
Niko Bellic
The protagonist and the character you control. Originally from the former Soviet republic of Belarus. He has come to Liberty City in search of a better life, and to find someone who has betrayed him.
Roman Bellic
Friend benefit: Car service. Call him for a free taxi anywhere in the city.
Niko's cousin. In the years since moving to Liberty City, he has built up a car service company.
Michelle
Niko's possible girlfriend. She asks a lot of questions, and sometimes seems confused about her past. Although she will call you for dates, she doesn't have a direct benefit to gameplay. If you call her late at night, she'll refuse to go out with you. You can press your luck after the first date.
Vladimir Glebov
Vladimir is a small time loanshark. He often harasses Roman, who owes him some money.
Little Jacob
Friend benefit: Gun dealer. Call him up and he'll tell you where to meet him to purchase guns (but not body armor). He sometimes helps out with missions.
Brucie Kibbutz
Friend benefit: access to car theft missions
Brucie is a fanatic about fitness, and routinely abuses steroids and other performance enhancing drugs. He is a friend of Roman's.
Mikhail Faustin
A leader of the Russian Mob.
Dimitri Rascalov
Faustin's right hand man.
Manny Escuela
Manny is a rapper who is trying to promote himself as a hero of the community.
Elizabetha Torres
Elizabetha is a drug dealer in the ??? section of Liberty City.
Playboy X
Possible friend A drug dealer who has achieved moderate success in his field.
Dwayne Forge
Possible friend Friend of Playboy X's, he was only recently released from prison.
Patrick "Packie" McReary
Part of the McReary crime family.
Francis McReary
A police officer who has something to hide. Sometimes works with Manny. Brother to Packie.
Ray Boccino
Sometime employer of Packie, found in Little Italy.
Karen
You can date Karen once you lock it by doing missions for Packie. You should not press your luck after the first date.