Backstory, backstory, backstory … it can make your main story if you do it right or seriously doom your main story if you do it wrong.
The reason you love backstory is because it’s the discovery of character. Turns out, that’s why readers love it too–but only if you use these 3 must-haves.
Source: The #1 Key to Relatable Characters: Backstory – Helping Writers Become Authors