I read this terrific article "How to Introduce a Character." Although it was written for novelists, the same character development strategies apply to screenplays. Try these tips:
1. Provide the character with a solid background study.
2. Have them carry an obsession or two.
3. Emotional crutches.
4. A chance to be ‘one of the guys’.
5. Be adversarial.
6. Sharp wit. Sharp Tongue. Pretty self-explanatory.
7. Healing relationship.
8. Secrets. Plenty and big.
Check out the entire article on Black Literature Magazine.