From Fire Emblem Wiki
Loosely, affinity determines a character's stat boosts that are gained from supports. Supports depend on the affinities of the two characters that are being bonded, and they determine the type of bonus given. The following tables are a compilation of bonuses given by the fire affinity in each game.
The Fire affinity gives offensive combat bonuses, and is usually desirable for characters with low attack power, or to maximize offensive potential with stronger characters. In the GBA games, it is considered superior to the similarly offensive Light affinity, because it gives an evasion bonus as well. Along with the Light affinity, it gives no Critical Evade on its own.
[edit] 
Fire Affinity Bonuses in Fire Emblem: Fūin no Tsurugi
| Support Level | Attack | Hit | Defense | Evasion | Critical
|
| C
| + 0.5% | + 2.5% | + 0.0% | + 2.5% | + 2.5%
|
| B
| + 1.0% | + 5.0% | + 0.0% | + 5.0% | + 5.0%
|
| A
| + 1.5% | + 7.5% | + 0.0% | + 7.5% | + 7.5%
|
[edit] Characters with the Fire affinity in Fire Emblem: Fūin no Tsurugi
Alan, Dorothy, Fir, Geese, Lugh, Roy, Wade, Wendy
[edit] Fire Affinity Bonuses in Fire Emblem: Rekka no Ken
| Support Level | Attack | Hit | Defense | Evasion | Critical
|
| C
| + 0.5% | + 2.5% | + 0.0% | + 2.5% | + 2.5%
|
| B
| + 1.0% | + 5.0% | + 0.0% | + 5.0% | + 5.0%
|
| A
| + 1.5% | + 7.5% | + 0.0% | + 7.5% | + 7.5%
|
[edit] Characters with the Fire affinity in Fire Emblem: Rekka no Ken
Dart, Dorcas, Guy, Harken, Lowen, Nino, Rebecca, Vaida
[edit] Fire Affinity Bonuses in Fire Emblem: The Sacred Stones
| Support Level | Attack | Hit | Defense | Evasion | Critical
|
| C
| + 0.5% | + 2.5% | + 0.0% | + 2.5% | + 2.5%
|
| B
| + 1.0% | + 5.0% | + 0.0% | + 5.0% | + 5.0%
|
| A
| + 1.5% | + 7.5% | + 0.0% | + 7.5% | + 7.5%
|
[edit] Characters with the Fire affinity in Fire Emblem: The Sacred Stones
Cormag, Ephraim, Fado, Garcia, Neimi, Ross, Tethys
[edit] 
Fire Affinity Bonuses in Fire Emblem: Path of Radiance
| Support Level | Attack | Hit | Defense | Evasion
|
| C
| + 0.5% | + 2.5% | + 0.0% | + 0.0%
|
| B
| + 1.0% | + 5.0% | + 0.0% | + 0.0%
|
| A
| + 1.5% | + 7.5% | + 0.0% | + 0.0%
|
[edit] Characters with the Fire affinity in Fire Emblem: Path of Radiance
Boyd, Devdan, Geoffrey, Marcia, Mia, Reyson, Rhys, Tormod
[edit] 
Fire Affinity Bonuses in Fire Emblem: Radiant Dawn
| Support Level | Attack | Hit | Defense | Evasion
|
| C
| + 0.5% | + 2.5% | + 0.0% | + 0.0%
|
| B
| + 1.0% | + 5.0% | + 0.0% | + 0.0%
|
| A
| + 1.5% | + 7.5% | + 0.0% | + 0.0%
|
[edit] Characters with the Fire affinity in Fire Emblem: Radiant Dawn
Boyd, Danved, Geoffrey, Heather, Marcia, Mia, Nealuchi, Oliver, Skrimir, Reyson, Rhys, Tormod
