Building strong relationships with certain characters in Grand Theft Auto IV unlocks valuable perks that can significantly aid Niko throughout the game. These perks range from free services to combat assistance. To maximize these benefits, you need to regularly interact with your friends and girlfriends.

Key Relationships & Perks:
| Character | Activity Preference | Perk (at 75% Like) | Perk (at 90% Like) |
|---|---|---|---|
| Roman Bellic | Bowling, Darts, Pool, Eating, Drinking | Free Taxi Rides (call him) | N/A |
| Little Jacob | Drinking, Darts, Pool, Eating, Strip Club | Discounted Weapons (call him) | N/A |
| Packie McReary | Drinking, Darts, Pool, Eating, Strip Club | Car Bomb Placement (call him) | N/A |
| Dwayne Forge | Drinking, Eating, Strip Club | Backup (call him for two armed thugs) | N/A |
| Carmen Ortiz (Girlfriend) | Eating, Drinking, Show, Strip Club | Health Boost (call her) | N/A |
| Kiki Jenkins (Girlfriend) | Bowling, Darts, Pool, Eating, Show | Removes 1 Wanted Star (call her) | N/A |
| Alexandra Chilton (Girlfriend) | Eating, Drinking, Show, Strip Club | Discount at Clothing Stores (call her) | N/A |
Maximizing Relationships:
- Accept Invitations: Always accept calls to hang out or go on dates.
- Initiate Contact: Call friends/girlfriends yourself if they haven't called in a while.
- Choose Preferred Activities: Take them to activities they enjoy (check their profile on the phone).
- Win Mini-Games: Winning at bowling, darts, or pool can slightly boost their 'Like' stat.
- Drive Carefully: When driving them, avoid crashes and reckless driving.
- Dress Appropriately: For dates, wear nice clothes.
Regular interaction is key. If you neglect a friend or girlfriend for too long, their 'Like' stat will decrease, and they may become unavailable for a while. Aim for at least 75% 'Like' to unlock their primary perk.