Grand Theft Auto 4 Guide - Friends
As you progress through the storyline, Niko will meet new people and make friends in Liberty City. You can arrange activities with these friends once they have been made by selecting one via their Phonebook menu, or you can wait for them to call you. Each friend has activities that they prefer, though they will most likely have a good time wherever you take them. Furthermore, each friend is only available during a certain time of the day, so you'll get their answering machine if you call them while they're not available. Your friends will like you more if you hang out with them and answer the phone when the call; they will come to resent you if you continuously turn down their invitations or neglect them.
Each friend has a special call-in ability which can be utilized once they like you enough. To unlock these abilities, hang out with these characters until their “Like” and “Respect” values are high enough. If their like and respect falls below the required percentage to unlock their special ability, it will be lost until you reach that percentage again.
Note: Roman and Dwayne are not needed to unlock the “Liberty City (5)” achievement on the Xbox 360 version, nor for the 100% completion requirements that involve friends.
Complete “Bleed Out” to gain Roman as a friend.
Special Ability: Taxi - Roman will send a cab that you can use free of charge.
Complete “Shadow” to gain Little Jacob as a friend.
Special Ability: Weapon Sale - Buy guns from Little Jacob at a reduced price, though his selection is limited.
Complete “No.1” to gain Brucie as a friend.
Special Ability: Helicopter - Brucie will fly to your location and pick you up in a helicopter.
Complete “Three Leaf Clover” to gain Packie as a friend.
Special Ability: Car Bomb - Packie will prepare a car bomb, which you can then plant on a car and use your phone to detonate.
Complete “The Holland Play” to gain Dwayne as a friend (if you make the right choice).
Special Ability: Back Up - Dwayne will send gang members to help you.