Bagpuss
Legend
Personally I house ruled that if an area spell hits one person in melee then it has a 50% chance of catching any character in direct melee with them (so long as they are also withing 5ft of the area of effect).
Basically it represents the melee moving back and forth as opponents thrust and sidestep. There is a chance the person might be thrusting towards the target when the fireball goes off and thus get caught.
The requirement to be within 5ft of the edge of the area effect is so the spell is still useful fighting larger monsters so you can catch the hind quarters (yes I know no facing) of a dragon while the fighter is at its business end some distance from the blast.
Basically it represents the melee moving back and forth as opponents thrust and sidestep. There is a chance the person might be thrusting towards the target when the fireball goes off and thus get caught.
The requirement to be within 5ft of the edge of the area effect is so the spell is still useful fighting larger monsters so you can catch the hind quarters (yes I know no facing) of a dragon while the fighter is at its business end some distance from the blast.